usb: chipidea: udc: remove unused value assignment

retval is assigned to be -EOVERFLOW but is overwritten later before
it's used, remove this unused value assignment.
Signed-off-by: Li Jun <jun.li@nxp.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>

drivers/usb/chipidea/udc.c

@@ -819,7 +819,6 @@ static int _ep_queue(struct usb_ep *ep, struct usb_request *req,
 			       ci->ep0out : ci->ep0in;
 		if (!list_empty(&hwep->qh.queue)) {
 			_ep_nuke(hwep);
-			retval = -EOVERFLOW;
 			dev_warn(hwep->ci->dev, "endpoint ctrl %X nuked\n",
 				 _usb_addr(hwep));
 		}