Input: atkbd - cancel delayed work before freeing its structure

Pointed out by Oleg Nesterov. Since delayed work is used here, use of
flush_scheduled_work() is not sufficient in atkbd_disconnect(). It does
not wait for scheduled delayed work to finish. This patch prevents
delayed work to be processed after freeing atkbd structure (used struct
delayed_work is part of atkbd) by cancelling this delayed work.
Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/keyboard/atkbd.c

@@ -824,7 +824,7 @@ static void atkbd_disconnect(struct serio *serio)
 	atkbd_disable(atkbd);
 
 	/* make sure we don't have a command in flight */
-	flush_scheduled_work();
+	cancel_delayed_work_sync(&atkbd->event_work);
 
 	sysfs_remove_group(&serio->dev.kobj, &atkbd_attribute_group);
 	input_unregister_device(atkbd->dev);