net/smc: no need to flush smcd_dev's event_wq before destroying it

destroy_workqueue() already calls drain_workqueue(), which is a stronger
variant of flush_workqueue().
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/smc/smc_ism.c

@@ -470,7 +470,6 @@ void smcd_unregister_dev(struct smcd_dev *smcd)
 	mutex_unlock(&smcd_dev_list.mutex);
 	smcd->going_away = 1;
 	smc_smcd_terminate_all(smcd);
-	flush_workqueue(smcd->event_wq);
 	destroy_workqueue(smcd->event_wq);
 
 	device_del(&smcd->dev);