mac80211: fix rx monitor filter refcounters

This patch fixes an refcounting bug. Previously it
was possible to corrupt the per-device recv. filter
and monitor management counters when:
	iw dev wlanX set monitor [new flags]
was issued on an active monitor interface.

Acked-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 945fbf2..f6a6d78 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1132,6 +1132,8 @@
 void ieee80211_remove_interfaces(struct ieee80211_local *local);
 u32 __ieee80211_recalc_idle(struct ieee80211_local *local);
 void ieee80211_recalc_idle(struct ieee80211_local *local);
+void ieee80211_adjust_monitor_flags(struct ieee80211_sub_if_data *sdata,
+				    const int offset);
 
 static inline bool ieee80211_sdata_running(struct ieee80211_sub_if_data *sdata)
 {