[FS#1458] brcmfmac: Missing stats - Bitrate, Signal / Noise for wifi radios and clients

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Vivek (npcomplete) 

Attached to Project - OpenWrt/LEDE Project
Summary - brcmfmac: Missing stats - Bitrate, Signal / Noise for wifi radios and clients
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Device: EA9500
Openwrt: trunk as of 26-Mar-2018
brcmfmac firmware ver: May  1 2017 12:43:53 version 10.10.122.301 (r658909) FWID 01-1ebebd8a

I don't notice any performance drop or connectivity issues. 
Just that I can't seem to gauge what speeds are being used etc. 

root at OpenWrt:~# iwinfo wlan0 assoclist
00:FC:8B:98:XX:XX  unknown / unknown (SNR 0)  7000 ms ago
        RX: unknown                                        0 Pkts.
        TX: unknown                                        0 Pkts.
        expected throughput: unknown

4C:66:41:AD:XX:XX  unknown / unknown (SNR 0)  2000 ms ago
        RX: unknown                                        0 Pkts.
        TX: unknown                                        0 Pkts.
        expected throughput: unknown

root at OpenWrt:~# iwinfo wlan1 assoclist
34:6F:92:05:XX:XX  unknown / unknown (SNR 0)  7000 ms ago
        RX: unknown                                        0 Pkts.
        TX: unknown                                        0 Pkts.
        expected throughput: unknown

FC:C2:DE:76:XX:XX  unknown / unknown (SNR 0)  26000 ms ago
        RX: unknown                                        0 Pkts.
        TX: unknown                                        0 Pkts.
        expected throughput: unknown

root at OpenWrt:~# iwinfo wlan2 assoclist
30:07:4D:74:XX:XX  unknown / unknown (SNR 0)  9000 ms ago
        RX: unknown                                        0 Pkts.
        TX: unknown                                        0 Pkts.
        expected throughput: unknown



root at OpenWrt:~# iw phy phy0 info
Wiphy phy0
        max # scan SSIDs: 10
        max scan IEs length: 2048 bytes
        max # sched scan SSIDs: 0
        max # match sets: 0
        max # scan plans: 1
        max scan plan interval: -1
        max scan plan iterations: 0
        Retry short limit: 7
        Retry long limit: 4
        Coverage class: 0 (up to 0m)
        Device supports roaming.
        Available Antennas: TX 0 RX 0
        Supported interface modes:
                 * IBSS
                 * managed
                 * AP
                 * P2P-client
                 * P2P-GO
                 * P2P-device
        Band 2:
                Capabilities: 0x1062
                        HT20/HT40
                        Static SM Power Save
                        RX HT20 SGI
                        RX HT40 SGI
                        No RX STBC
                        Max AMSDU length: 3839 bytes
                        DSSS/CCK HT40
                Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
                Minimum RX AMPDU time spacing: 16 usec (0x07)
                HT TX/RX MCS rate indexes supported: 0-31
                VHT Capabilities (0x0c1b4064):
                        Max MPDU length: 3895
                        Supported Channel Width: 160 MHz
                        short GI (80 MHz)
                        short GI (160/80+80 MHz)
                        MU Beamformer
                        MU Beamformee
                VHT RX MCS set:
                        1 streams: MCS 0-9
                        2 streams: MCS 0-9
                        3 streams: MCS 0-9
                        4 streams: MCS 0-9
                        5 streams: not supported
                        6 streams: not supported
                        7 streams: not supported
                        8 streams: not supported
                VHT RX highest supported: 0 Mbps
                VHT TX MCS set:
                        1 streams: MCS 0-9
                        2 streams: MCS 0-9
                        3 streams: MCS 0-9
                        4 streams: MCS 0-9
                        5 streams: not supported
                        6 streams: not supported
                        7 streams: not supported
                        8 streams: not supported
                VHT TX highest supported: 0 Mbps
                Frequencies:
                        * 5170 MHz [34] (disabled)
                        * 5180 MHz [36] (20.0 dBm)
                        * 5190 MHz [38] (20.0 dBm)
                        * 5200 MHz [40] (20.0 dBm)
                        * 5210 MHz [42] (20.0 dBm)
                        * 5220 MHz [44] (20.0 dBm)
                        * 5230 MHz [46] (20.0 dBm)
                        * 5240 MHz [48] (20.0 dBm)
                        * 5260 MHz [52] (20.0 dBm) (radar detection)
                        * 5280 MHz [56] (20.0 dBm) (radar detection)
                        * 5300 MHz [60] (20.0 dBm) (radar detection)
                        * 5320 MHz [64] (20.0 dBm) (radar detection)
                        * 5500 MHz [100] (20.0 dBm) (radar detection)
                        * 5520 MHz [104] (20.0 dBm) (radar detection)
                        * 5540 MHz [108] (20.0 dBm) (radar detection)
                        * 5560 MHz [112] (20.0 dBm) (radar detection)
                        * 5580 MHz [116] (20.0 dBm) (radar detection)
                        * 5600 MHz [120] (20.0 dBm) (radar detection)
                        * 5620 MHz [124] (20.0 dBm) (radar detection)
                        * 5640 MHz [128] (20.0 dBm) (radar detection)
                        * 5660 MHz [132] (20.0 dBm) (radar detection)
                        * 5680 MHz [136] (20.0 dBm) (radar detection)
                        * 5700 MHz [140] (20.0 dBm) (radar detection)
                        * 5720 MHz [144] (20.0 dBm) (radar detection)
                        * 5745 MHz [149] (20.0 dBm)
                        * 5765 MHz [153] (20.0 dBm)
                        * 5785 MHz [157] (20.0 dBm)
                        * 5805 MHz [161] (20.0 dBm)
                        * 5825 MHz [165] (20.0 dBm)
        valid interface combinations:
                 * #{ managed }