usb: gadget: remove redundant self assignment

The assignment ret = ret is redundant and can be removed.
Reviewed-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/core.c

@@ -107,10 +107,8 @@ int usb_ep_enable(struct usb_ep *ep)
 		goto out;
 
 	ret = ep->ops->enable(ep, ep->desc);
-	if (ret) {
-		ret = ret;
+	if (ret)
 		goto out;
-	}
 
 	ep->enabled = true;