usb: gadget: udc: atmel: check rc of devm_gpiod_get_optional()

devm_gpiod_get_optional() might still return an error code, esp.
EPROBE_DEFER. Return any errors.
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20220705131951.1388968-1-michael@walle.ccSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/atmel_usba_udc.c

@@ -2165,6 +2165,8 @@ static struct usba_ep * atmel_udc_of_init(struct platform_device *pdev,
 
 	udc->vbus_pin = devm_gpiod_get_optional(&pdev->dev, "atmel,vbus",
 						GPIOD_IN);
+	if (IS_ERR(udc->vbus_pin))
+		return ERR_CAST(udc->vbus_pin);
 
 	if (fifo_mode == 0) {
 		udc->num_ep = udc_config->num_ep;