media: rc: clean the freed urb pointer to avoid double free

After freed rx_urb, we should set the second interface urb to NULL,
otherwise a double free would happen when the driver is removed
from the first interface.

Signed-off-by: Nil Yi <[e-mail]>
Signed-off-by: Sean Young <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/rc/imon.c

···
 touch_setup_failed:
 find_endpoint_failed:
 	usb_put_dev(ictx->usbdev_intf1);
+	ictx->usbdev_intf1 = NULL;
 	mutex_unlock(&ictx->lock);
 	usb_free_urb(rx_urb);
+	ictx->rx_urb_intf1 = NULL;
 rx_urb_alloc_failed:
 	dev_err(ictx->dev, "unable to initialize intf1, err %d\n", ret);