mac80211: optimise station flags

The flaglock in struct sta_info has long been
something that I wanted to get rid of, this
finally does the conversion to atomic bitops.

The conversion itself is straight-forward in
most places, a few things needed to change a
bit since we can no longer use multiple bits
at the same time.

On x86-64, this is a fairly significant code
size reduction:
   text	   data	    bss	    dec	    hex
 427861	  23648	   1008	 452517	  6e7a5	before
 425383	  23648	    976	 450007	  6ddd7	after

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 60dc600..7439d26 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -1122,7 +1122,7 @@
 
 		list_for_each_entry(sta, &local->sta_list, list) {
 			ieee80211_sta_tear_down_BA_sessions(sta, true);
-			clear_sta_flags(sta, WLAN_STA_BLOCK_BA);
+			clear_sta_flag(sta, WLAN_STA_BLOCK_BA);
 		}
 
 		mutex_unlock(&local->sta_mtx);