mac80211: fix uninitialized variable

CSA completion could call in a driver
bss_info_changed() with a garbled `changed` flag
leading to all sorts of problems.

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

net/mac80211/cfg.c

@@ -2962,7 +2962,7 @@ void ieee80211_csa_finalize_work(struct work_struct *work)
 		container_of(work, struct ieee80211_sub_if_data,
 			     csa_finalize_work);
 	struct ieee80211_local *local = sdata->local;
-	int err, changed;
+	int err, changed = 0;
 
 	if (!ieee80211_sdata_running(sdata))
 		return;