s390/ccwgroup: exploit ccwdev_by_dev_id

Instead of finding devices via driver_find_device use the bus_find_device
wrapper get_ccwdev_by_dev_id. This allows us to get rid of the ccw_driver
argument of ccwgroup_create_dev and thus simplify the interface.

Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
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/device.h b/drivers/s390/cio/device.h
index 179824b..6bace69 100644
--- a/drivers/s390/cio/device.h
+++ b/drivers/s390/cio/device.h
@@ -101,6 +101,7 @@
 void ccw_device_schedule_sch_unregister(struct ccw_device *);
 int ccw_purge_blacklisted(void);
 void ccw_device_sched_todo(struct ccw_device *cdev, enum cdev_todo todo);
+struct ccw_device *get_ccwdev_by_dev_id(struct ccw_dev_id *dev_id);
 
 /* Function prototypes for device status and basic sense stuff. */
 void ccw_device_accumulate_irb(struct ccw_device *, struct irb *);