scheduled scan api

[Arend van Spriel]

Hi Johannes,

I received a couple of reports from people who got problem with brcmfmac 
when a scheduled scan is requested, without any ssid specified. 
Currently, brcmfmac basically rejects the request. So what are valid 
usage scenarios for scheduled scans with respect to the n_ssid, 
n_channels, and n_matchsets. In the kernel doc below it says a 
zero-length ssid means 'no match'. I suppose it means any ssid which 
signal is above RRSI threshold will match.

Regards,
Arend
---8<----------------------------------------------------------
/**
  * struct cfg80211_match_set - sets of attributes to match
  *
  * @ssid: SSID to be matched; may be zero-length for no match (RSSI only)
  * @rssi_thold: don't report scan results below this threshold (in s32 dBm)
  */