dfu: Detach the controller on error

In case anything errors out during the DFU registration, detach
the controller instead of bailing out right away. This way, the
controller can be reattached on next attempt.

Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Signed-off-by: Marek Vasut <marex@denx.de>

common/dfu.c

@@ -34,7 +34,8 @@ int run_usb_dnl_gadget(int usbctrl_index, char *usb_dnl_gadget)
 	ret = g_dnl_register(usb_dnl_gadget);
 	if (ret) {
 		pr_err("g_dnl_register failed");
-		return CMD_RET_FAILURE;
+		ret = CMD_RET_FAILURE;
+		goto err_detach;
 	}
 
 #ifdef CONFIG_DFU_TIMEOUT
@@ -106,6 +107,7 @@ int run_usb_dnl_gadget(int usbctrl_index, char *usb_dnl_gadget)
 	}
 exit:
 	g_dnl_unregister();
+err_detach:
 	usb_gadget_release(usbctrl_index);
 
 	if (dfu_reset)