mtip32xx: release the semaphore on an error path

Release the semaphore in an error path in mtip_hw_get_scatterlist(). This
fixes the smatch warning inconsistent returns.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/mtip32xx/mtip32xx.c

@@ -2510,8 +2510,10 @@ static struct scatterlist *mtip_hw_get_scatterlist(struct driver_data *dd,
 		up(&dd->port->cmd_slot);
 		return NULL;
 	}
-	if (unlikely(*tag < 0))
+	if (unlikely(*tag < 0)) {
+		up(&dd->port->cmd_slot);
 		return NULL;
+	}
 
 	return dd->port->commands[*tag].sg;
 }