No reason to delay it until image_id is known.  This will be required
by some rbd_obj_method_sync() callers, after rbd_obj_method_sync() is
changed to take oloc.
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
Reviewed-by: NJason Dillaman <dillaman@redhat.com>