usb: gadget: at91_udc: remove unused release function

As the driver call usb_add_gadget_udc --> usb_add_gadget_udc_release
with NULL as release parameter, so it will use usb_udc_no_release.
So, the release in driver won't used, remove it.

And at the same time, in the usb_add_gadget_udc_release will set the
gadget name, so remove it also in driver.
Signed-off-by: NBo Shen <voice.shen@atmel.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>

drivers/usb/gadget/udc/at91_udc.c

@@ -1537,20 +1537,11 @@ static irqreturn_t at91_udc_irq (int irq, void *_udc)
 
 /*-------------------------------------------------------------------------*/
 
-static void nop_release(struct device *dev)
-{
-	/* nothing to free */
-}
-
 static struct at91_udc controller = {
 	.gadget = {
 		.ops	= &at91_udc_ops,
 		.ep0	= &controller.ep[0].ep,
 		.name	= driver_name,
-		.dev	= {
-			.init_name = "gadget",
-			.release = nop_release,
-		}
 	},
 	.ep[0] = {
 		.ep = {