mac80211: refactor monitor representation in sdata

Insert the u32 monitor flags variable in a new structure
that represents a monitor interface.
This will allow to add more configuration variables to
that structure which will happen in an upcoming change.

Signed-off-by: Aviya Erenfeld <aviya.erenfeld@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -824,6 +824,10 @@ struct txq_info {
 	struct ieee80211_txq txq;
 };
 
+struct ieee80211_if_mntr {
+	u32 flags;
+};
+
 struct ieee80211_sub_if_data {
 	struct list_head list;
 
@@ -922,7 +926,7 @@ struct ieee80211_sub_if_data {
 		struct ieee80211_if_ibss ibss;
 		struct ieee80211_if_mesh mesh;
 		struct ieee80211_if_ocb ocb;
-		u32 mntr_flags;
+		struct ieee80211_if_mntr mntr;
 	} u;
 
 #ifdef CONFIG_MAC80211_DEBUGFS