atmel_usba_udc: Kill GPIO_PIN_NONE

GPIO_PIN_NONE should no longer be used. Replace it with a simple
test against negative values.

This is a transitional patch, waiting for gpio_is_valid() to be
merged at which point the tests should be revisited.

Signed-off-by: Stelian Pop <[e-mail]>
Acked-by: David Brownell <[e-mail]>
Signed-off-by: Haavard Skinnemoen <[e-mail]>

drivers/usb/gadget/atmel_usba_udc.c

···
 		goto err_device_add;
 	}
 
-	if (pdata && pdata->vbus_pin != GPIO_PIN_NONE) {
+	if (pdata && pdata->vbus_pin >= 0) {
 		if (!gpio_request(pdata->vbus_pin, "atmel_usba_udc")) {
 			udc->vbus_pin = pdata->vbus_pin;