mac80211: add support for MU-MIMO air sniffer

add support to MU-MIMO air sniffer according groupID:
in monitor mode, use a given MU-MIMO groupID to monitor stations
that belongs to that group using MU-MIMO.

add support for following a station according to its MAC address
using VHT MU-MIMO sniffer:
the monitors wait until they get an action MU-MIMO notification
frame, then parses it in order to find the groupID that corresponds
to the given MAC address and monitors packets destined to that
groupID using VHT MU-MIMO.

Signed-off-by: Aviya Erenfeld <aviya.erenfeld@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/driver-ops.h

@@ -162,7 +162,8 @@ static inline void drv_bss_info_changed(struct ieee80211_local *local,
 		return;
 
 	if (WARN_ON_ONCE(sdata->vif.type == NL80211_IFTYPE_P2P_DEVICE ||
-			 sdata->vif.type == NL80211_IFTYPE_MONITOR))
+			 (sdata->vif.type == NL80211_IFTYPE_MONITOR &&
+			  !sdata->vif.mu_mimo_owner)))
 		return;
 
 	if (!check_sdata_in_driver(sdata))