cfg80211: clean up beacon loss CQM event

Having it as a sub-event for RSSI thresholds is very ugly,
but luckily no userspace actually uses the events yet.

Move the event to its own function call internally and to
its own event attribute in nl80211.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -4671,6 +4671,14 @@ void ieee80211_cqm_rssi_notify(struct ieee80211_vif *vif,
 			       enum nl80211_cqm_rssi_threshold_event rssi_event,
 			       gfp_t gfp);
 
+/**
+ * ieee80211_cqm_beacon_loss_notify - inform CQM of beacon loss
+ *
+ * @vif: &struct ieee80211_vif pointer from the add_interface callback.
+ * @gfp: context flags
+ */
+void ieee80211_cqm_beacon_loss_notify(struct ieee80211_vif *vif, gfp_t gfp);
+
 /**
  * ieee80211_radar_detected - inform that a radar was detected
  *