mac80211: don't clear sched_scan_sdata on sched scan stop request

ieee80211_request_sched_scan_stop() cleared
local->sched_scan_sdata. However, sched_scan_sdata
should be cleared only after the driver calls
ieee80211_sched_scan_stopped() (like with normal hw scan).

Clearing sched_scan_sdata too early caused
ieee80211_sched_scan_stopped_work to exit prematurely
without properly cleaning all the sched scan resources
and without calling cfg80211_sched_scan_stopped (so
userspace wasn't notified about sched scan completion).
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/scan.c

@@ -984,7 +984,6 @@ int ieee80211_request_sched_scan_stop(struct ieee80211_sub_if_data *sdata)
 			kfree(local->sched_scan_ies.ie[i]);
 
 		drv_sched_scan_stop(local, sdata);
-		rcu_assign_pointer(local->sched_scan_sdata, NULL);
 	}
 out:
 	mutex_unlock(&local->mtx);