[S390] cio: Use ccw_dev_id and subchannel_id in ccw_device_private

Use the proper structures to identify device and subchannel. Change
get_disc_ccwdev_by_devno() to get_disc_ccwdev_by_dev_id().

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/include/asm-s390/cio.h b/include/asm-s390/cio.h
index da063cd..81287d8 100644
--- a/include/asm-s390/cio.h
+++ b/include/asm-s390/cio.h
@@ -275,6 +275,12 @@
 	u16 devno;
 };
 
+static inline int ccw_dev_id_is_equal(struct ccw_dev_id *dev_id1,
+				      struct ccw_dev_id *dev_id2)
+{
+	return !memcmp(dev_id1, dev_id2, sizeof(struct ccw_dev_id));
+}
+
 extern int diag210(struct diag210 *addr);
 
 extern void wait_cons_dev(void);