[S390] cio: use exception-save stsch

Using stsch on schids with ssid != 0 can lead to an operand
exception. Use stsch_err to handle potential exceptions
if we fail to reenable mss after hibernation.

Cc: <stable@kernel.org>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/cio/chsc_sch.c b/drivers/s390/cio/chsc_sch.c
index 404f630..3b6f4ad 100644
--- a/drivers/s390/cio/chsc_sch.c
+++ b/drivers/s390/cio/chsc_sch.c
@@ -124,7 +124,7 @@
 	 * since we don't have a way to clear the subchannel and
 	 * cannot disable it with a request running.
 	 */
-	cc = stsch(sch->schid, &schib);
+	cc = stsch_err(sch->schid, &schib);
 	if (!cc && scsw_stctl(&schib.scsw))
 		return -EAGAIN;
 	return 0;