usb: gadget: udc-xilinx: remove redundant pointer udc

Pointer udc is assigned but never read, hence it is redundant and
can be removed. Cleans up clang warning:

drivers/usb/gadget/udc/udc-xilinx.c:974:2: warning: Value stored
to 'udc' is never read
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NFelipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/udc-xilinx.c

@@ -963,10 +963,8 @@ static struct usb_request *xudc_ep_alloc_request(struct usb_ep *_ep,
 						 gfp_t gfp_flags)
 {
 	struct xusb_ep *ep = to_xusb_ep(_ep);
-	struct xusb_udc *udc;
 	struct xusb_req *req;
 
-	udc = ep->udc;
 	req = kzalloc(sizeof(*req), gfp_flags);
 	if (!req)
 		return NULL;