[S390] cio: Catch operand exceptions on stsch.

If we have a subchannel id which has been generated via
for_each_subchannel(), it might contain an invalid subchannel set id.
We need to catch the ensuing operand exception by using stsch_err()
instead of stsch() in all possible cases.

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/chsc.c b/drivers/s390/cio/chsc.c
index 15b0e63..514daea 100644
--- a/drivers/s390/cio/chsc.c
+++ b/drivers/s390/cio/chsc.c
@@ -608,7 +608,7 @@
 	struct schib schib;
 	int ret;
 
-	if (stsch(schid, &schib))
+	if (stsch_err(schid, &schib))
 		/* We're through */
 		return need_rescan ? -EAGAIN : -ENXIO;