Currently background scanning with wpa_supplicant does not work very
well because rtl8812au does not notify it about changes to RSSI. To
fix this:
* Implement the cfg80211_ops::set_cqm_rssi_config operation to set the
parameters for RSSI notifications.
* Add a rtw_cfg80211_cqm_rssi_update() function that calls
cfg80211_cqm_rssi_notify() if the RSSI has changed significantly
(based on those parameters).
* When connected in infrastructure mode, call
rtw_cfg80211_cqm_rssi_update() after processing a beacon and
updating the RSSI.
Signed-off-by: Ben Hutchings <ben.hutchings@mind.be>
