rbd: remove duplicate calls to rbd_dev_mapping_clear()

Commit d1cf5788 ("rbd: set mapping info earlier") defined
rbd_dev_mapping_clear(), but, just a few days after, commit
f35a4dee ("rbd: set the mapping size and features later") moved
rbd_dev_mapping_set() calls and added another rbd_dev_mapping_clear()
call instead of moving the old one.  Around the same time, another
duplicate was introduced in rbd_dev_device_release() - kill both.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

drivers/block/rbd.c

@@ -5254,8 +5254,6 @@ static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
 		unregister_blkdev(rbd_dev->major, rbd_dev->name);
 err_out_id:
 	rbd_dev_id_put(rbd_dev);
-	rbd_dev_mapping_clear(rbd_dev);
-
 	return ret;
 }
 
@@ -5510,7 +5508,6 @@ static void rbd_dev_device_release(struct rbd_device *rbd_dev)
 	if (!single_major)
 		unregister_blkdev(rbd_dev->major, rbd_dev->name);
 	rbd_dev_id_put(rbd_dev);
-	rbd_dev_mapping_clear(rbd_dev);
 }
 
 static void rbd_dev_remove_parent(struct rbd_device *rbd_dev)