We have both uvc_init_video() and uvc_video_init() calls which can be
quite confusing to determine the process for each. Now that video
uvc_video_enable() has been renamed to uvc_video_start_streaming(),
adapt these calls to suit the new flow.
Rename uvc_init_video() to uvc_video_start_transfer() and
uvc_uninit_video() to uvc_video_stop_transfer().