mac80211: check fast-xmit if IBSS STA QoS changed

When an IBSS station gets QoS enabled after having been added,
check fast-xmit to make sure the QoS header gets added to the
cache properly and frames can go out with QoS and higher rates.

Reported-by: Janusz Dziedzic <janusz.dziedzic@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index bfef1b2..21716af 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -1031,8 +1031,11 @@
 		}
 	}
 
-	if (sta && elems->wmm_info && local->hw.queues >= IEEE80211_NUM_ACS)
+	if (sta && !sta->sta.wme &&
+	    elems->wmm_info && local->hw.queues >= IEEE80211_NUM_ACS) {
 		sta->sta.wme = true;
+		ieee80211_check_fast_xmit(sta);
+	}
 
 	if (sta && elems->ht_operation && elems->ht_cap_elem &&
 	    sdata->u.ibss.chandef.width != NL80211_CHAN_WIDTH_20_NOHT &&