cfg80211: track ibss fixed channel

IBSS may hop between channels. It is necessary to
account this special case when considering
interface combinations.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -2411,6 +2411,8 @@ struct wireless_dev {
 	/* for AP and mesh channel tracking */
 	struct ieee80211_channel *channel;
 
+	bool ibss_fixed;
+
 	bool ps;
 	int ps_timeout;