vendor_elements not working with RPi4 Broadcomm Chip

[Peter Torelli]

I'm experimenting with `vendor_elements` on a Raspberry Pi and it
works fine with an EDUP USB wifi adapter, but not with the built-in
Broadcom wifi. There aren't any error messages indicating a problem,
and I can see the `beacon_ies` field set properly in the verbose
hostapd log output in both cases. The data doesn't show up on
wireshark for the BCM chip, unlike the EDUP.

This is with the latest Rasbian image (buster) and the latest git pull
of hostapd (hostapd v2.10-devel-hostap_2_9-1547-gdb599dbe9).

Peter