drbd: get rid of empty statement in is_valid_state

This should silence a warning about an empty statement. Thanks to Fabian
Frederick <fabf@skynet.be> who sent a patch I modified to be smaller and
avoids an additional indent level.
Signed-off-by: Roland Kammerer <roland.kammerer@linbit.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/drbd/drbd_state.c

@@ -814,7 +814,7 @@ is_valid_state(struct drbd_device *device, union drbd_state ns)
 	}
 
 	if (rv <= 0)
-		/* already found a reason to abort */;
+		goto out; /* already found a reason to abort */
 	else if (ns.role == R_SECONDARY && device->open_cnt)
 		rv = SS_DEVICE_IN_USE;
 
@@ -862,6 +862,7 @@ is_valid_state(struct drbd_device *device, union drbd_state ns)
 	else if (ns.conn >= C_CONNECTED && ns.pdsk == D_UNKNOWN)
 		rv = SS_CONNECTED_OUTDATES;
 
+out:
 	rcu_read_unlock();
 
 	return rv;