media: video-i2c: use vb2_video_unregister_device on driver removal

media: video-i2c: use vb2_video_unregister_device on driver removal

The driver uses vb2_fop_release() as its file release operation, so
vb2_video_unregister_device() should be used instead of
video_unregister_device() during driver removal.

This ensures that the vb2 queue is properly disconnected before the
video device is unregistered.

Signed-off-by: Arash Golgol <arash.golgol@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>