mac80211: per interface idle notification

Sometimes we don't just need to know whether or
not the device is idle, but also per interface.
This adds that reporting capability to mac80211.

Signed-off-by: Johannes Berg <johannes.berg@intel.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 b44e03a..98e783c 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -497,6 +497,9 @@
 	 */
 	bool ht_opmode_valid;
 
+	/* to detect idle changes */
+	bool old_idle;
+
 	/* Fragment table for host-based reassembly */
 	struct ieee80211_fragment_entry	fragments[IEEE80211_FRAGMENT_MAX];
 	unsigned int fragment_next;