'current_state' is uninitialized in rbd_object_map_update_finish()

[Tony Lu]

Hello,

There is a warning during compiling driver rbd for uninitialized
'current state' in rbd_object_map_update_finish():
	
drivers/block/rbd.c: In function 'rbd_object_map_callback':
drivers/block/rbd.c:2122:21: warning: ‘current_state’ may be used uninitialized in this function [-Wmaybe-uninitialized]
      (current_state == OBJECT_EXISTS && state == OBJECT_EXISTS_CLEAN))

drivers/block/rbd.c:2090:23: note: ‘current_state’ was declared here
  u8 state, new_state, current_state;
                       ^~~~~~~~~~~~~

Cheers.
Tony Lu