usb: gadget: remove redundant self assignment

The assignment ret = ret is redundant and can be removed.
Reviewed-by: NKrzysztof Opasiak <k.opasiak@samsung.com>
Reviewed-by: NPeter Chen <peter.chen@nxp.com>
Signed-off-by: NStefan Agner <stefan@agner.ch>
Signed-off-by: NFelipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/core.c

@@ -139,10 +139,8 @@ int usb_ep_disable(struct usb_ep *ep)
 		goto out;
 
 	ret = ep->ops->disable(ep);
-	if (ret) {
-		ret = ret;
+	if (ret)
 		goto out;
-	}
 
 	ep->enabled = false;