mac80211: wait for scan work complete before restarting hw

This is needed to avoid warning in ieee80211_restart_hw about hardware
scan in progress.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Wey-Yi W Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/main.c

@@ -305,6 +305,9 @@ void ieee80211_restart_hw(struct ieee80211_hw *hw)
 
 	trace_api_restart_hw(local);
 
+	/* wait for scan work complete */
+	flush_workqueue(local->workqueue);
+
 	WARN(test_bit(SCAN_HW_SCANNING, &local->scanning),
 		"%s called with hardware scan in progress\n", __func__);