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 <stelian@popies.net>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

drivers/usb/gadget/atmel_usba_udc.c

@@ -1937,7 +1937,7 @@ static int __init usba_udc_probe(struct platform_device *pdev)
 		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;