can: ucan: remove set but not used variable 'udev'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/net/can/usb/ucan.c: In function 'ucan_disconnect':
drivers/net/can/usb/ucan.c:1578:21: warning:
 variable 'udev' set but not used [-Wunused-but-set-variable]
  struct usb_device *udev;
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Martin Elshuber <martin.elshuber@theobroma-systems.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/usb/ucan.c

@@ -1575,11 +1575,8 @@ static int ucan_probe(struct usb_interface *intf,
 /* disconnect the device */
 static void ucan_disconnect(struct usb_interface *intf)
 {
-	struct usb_device *udev;
 	struct ucan_priv *up = usb_get_intfdata(intf);
 
-	udev = interface_to_usbdev(intf);
-
 	usb_set_intfdata(intf, NULL);
 
 	if (up) {