iwlwifi: mvm: Avoid signal based decisions if ave beacon RSSI is 0

If for some reason statistics notification received from the firmware
reports 0 in average beacon RSSI value, then skip it and avoid signal
based decisions.
Signed-off-by: Alexander Bondar <alexander.bondar@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/iwlwifi/mvm/rx.c

@@ -478,6 +478,11 @@ static void iwl_mvm_stat_iterator(void *_data, u8 *mac,
 	if (vif->type != NL80211_IFTYPE_STATION)
 		return;
 
+	if (sig == 0) {
+		IWL_DEBUG_RX(mvm, "RSSI is 0 - skip signal based decision\n");
+		return;
+	}
+
 	mvmvif->bf_data.ave_beacon_signal = sig;
 
 	/* BT Coex */