mac80211: sparse RCU annotations

This adds sparse RCU annotations to most of
mac80211, only the mesh code remains to be
done.

Due the the previous patches, the annotations
are pretty simple. The only thing that this
actually changes is removing the RCU usage of
key->sta in debugfs since this pointer isn't
actually an RCU-managed pointer (it only has
a single assignment done before the key even
goes live). As that is otherwise harmless, I
decided to make it part of this patch.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/mesh.h b/net/mac80211/mesh.h
index 5c0c2038..e7c5fdd 100644
--- a/net/mac80211/mesh.h
+++ b/net/mac80211/mesh.h
@@ -92,7 +92,7 @@
 	u8 dst[ETH_ALEN];
 	u8 mpp[ETH_ALEN];	/* used for MPP or MAP */
 	struct ieee80211_sub_if_data *sdata;
-	struct sta_info *next_hop;
+	struct sta_info __rcu *next_hop;
 	struct timer_list timer;
 	struct sk_buff_head frame_queue;
 	struct rcu_head rcu;