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>
 /* 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) {