mac80211: don't look up stations for multicast addresses

Since multicast addresses don't exist as stations, don't attempt
to look them up in the hashtable on TX.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 88a18ff..0e56ac5 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1172,7 +1172,7 @@
 		   tx->sdata->control_port_protocol == tx->skb->protocol) {
 		tx->sta = sta_info_get_bss(sdata, hdr->addr1);
 	}
-	if (!tx->sta)
+	if (!tx->sta && !is_multicast_ether_addr(hdr->addr1))
 		tx->sta = sta_info_get(sdata, hdr->addr1);
 
 	if (tx->sta && ieee80211_is_data_qos(hdr->frame_control) &&