CVE-2026-93101: fallo en Linux

In the Linux kernel, the following vulnerability has been resolved: media: v4l2-async: Unregister sub-device if asc_list is empty When my em28xx USB device that uses the i2c tvp5150 driver is disconnected, it crashes. The cause is that the tvp5150 i2c module uses v4l2_async, but the em28xx driver does not since it predates v4l2_async. In that corner case sd->asc_list is empty, so v4l2_async_unregister_subdev() never calls v4l2_device_unregister_subdev(). Modify the code so that, if sd->asc_list is empty, v4l2_device_unregister_subdev() is still called.