mac80211: annotate station rcu dereferences

The new RCU lockdep support warns about these
in some contexts -- make it aware of the locks
used to protect all this. Different locks are
used in different contexts which unfortunately
means we can't get perfect checking.

Also remove rcu_dereference() from two places
that don't actually dereference the pointers.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 06c33b6..b887e48 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -225,11 +225,11 @@
 			switch (sdata->vif.type) {
 			case NL80211_IFTYPE_AP:
 				sdata->vif.bss_conf.enable_beacon =
-					!!rcu_dereference(sdata->u.ap.beacon);
+					!!sdata->u.ap.beacon;
 				break;
 			case NL80211_IFTYPE_ADHOC:
 				sdata->vif.bss_conf.enable_beacon =
-					!!rcu_dereference(sdata->u.ibss.presp);
+					!!sdata->u.ibss.presp;
 				break;
 			case NL80211_IFTYPE_MESH_POINT:
 				sdata->vif.bss_conf.enable_beacon = true;