mac80211: set IEEE80211_TX_CTL_REQ_TX_STATUS on nullframes

The connection monitor needs to know the tx status of
nullframes to work properly.
Signed-off-by: Pontus Fuchs <pontus.fuchs@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mlme.c

@@ -880,6 +880,10 @@ void ieee80211_send_nullfunc(struct ieee80211_local *local,
 
 	IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT |
 					IEEE80211_TX_INTFL_OFFCHAN_TX_OK;
+
+	if (local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS)
+		IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_CTL_REQ_TX_STATUS;
+
 	if (ifmgd->flags & (IEEE80211_STA_BEACON_POLL |
 			    IEEE80211_STA_CONNECTION_POLL))
 		IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_CTL_USE_MINRATE;