usbip: clean up an indentation issue

There is a return statement that is indented incorrectly, fix this.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20190927092000.19373-1-colin.king@canonical.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/usbip/stub_tx.c

@@ -291,7 +291,7 @@ static int stub_send_ret_submit(struct stub_device *sdev)
 				kfree(iov);
 				usbip_event_add(&sdev->ud,
 						SDEV_EVENT_ERROR_TCP);
-			   return -1;
+				return -1;
 			}
 		}