[S390] cio: Register/unregister subchannels only from kslowcrw.

Make sure all subchannel handling is done on the slow path workqueue
so that we don't have races between an old subchannel unregistering
and a new subchannel with the same name registering.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 838f7ac..6db3108 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -483,7 +483,7 @@
 void css_schedule_reprobe(void)
 {
 	need_reprobe = 1;
-	queue_work(ccw_device_work, &css_reprobe_work);
+	queue_work(slow_path_wq, &css_reprobe_work);
 }
 
 EXPORT_SYMBOL_GPL(css_schedule_reprobe);