mac80211: ibss: use beacon_data struct for beacon and probe response

Instead of having an SKB all the time, use a beacon_data struct
with just the information required. This also allows removing a
synchronize_rcu() and using kfree_rcu() instead.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 55155e3..c7f8b8b 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -508,8 +508,7 @@
 
 	unsigned long ibss_join_req;
 	/* probe response/beacon for IBSS */
-	struct sk_buff __rcu *presp;
-	struct sk_buff *skb;
+	struct beacon_data __rcu *presp;
 
 	spinlock_t incomplete_lock;
 	struct list_head incomplete_stations;