s390/cio: remove pm support from IO subchannel drivers

The power-management functions are unused since the
'commit 39421627 ("s390: remove broken hibernate / power
management support")'. Remove these unused pm callbacks from
io-subchannel drivers.
Signed-off-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

drivers/s390/cio/device.c

@@ -149,19 +149,6 @@ static struct css_device_id io_subchannel_ids[] = {
 	{ /* end of list */ },
 };
 
-static int io_subchannel_prepare(struct subchannel *sch)
-{
-	struct ccw_device *cdev;
-	/*
-	 * Don't allow suspend while a ccw device registration
-	 * is still outstanding.
-	 */
-	cdev = sch_get_cdev(sch);
-	if (cdev && !device_is_registered(&cdev->dev))
-		return -EAGAIN;
-	return 0;
-}
-
 static int io_subchannel_settle(void)
 {
 	int ret;
@@ -186,7 +173,6 @@ static struct css_driver io_subchannel_driver = {
 	.probe = io_subchannel_probe,
 	.remove = io_subchannel_remove,
 	.shutdown = io_subchannel_shutdown,
-	.prepare = io_subchannel_prepare,
 	.settle = io_subchannel_settle,
 };