usb: lthor: Specify correct parameter for sizeof type

This patch removes this warning:
  CC      drivers/usb/gadget/f_thor.o
drivers/usb/gadget/f_thor.c: In function ‘thor_tx_data’:
drivers/usb/gadget/f_thor.c:572:2: warning: format ‘%d’ expects argument
of type ‘int’, but argument 4 has type ‘long unsigned int’ [-Wformat=]
  debug("%s: dev->in_req->length:%d to_cpy:%d\n", __func__,
  ^

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

drivers/usb/gadget/f_thor.c

@@ -569,7 +569,7 @@ static void thor_tx_data(unsigned char *data, int len)
 
 	dev->in_req->length = len;
 
-	debug("%s: dev->in_req->length:%d to_cpy:%d\n", __func__,
+	debug("%s: dev->in_req->length:%d to_cpy:%zd\n", __func__,
 	      dev->in_req->length, sizeof(data));
 
 	status = usb_ep_queue(dev->in_ep, dev->in_req, 0);