radv: Enable KHR_video_queue if encode is enabled
What does this MR do and why?
radv: Enable KHR_video_queue if encode is enabled
KHR_video_encode_queue is dependent on KHR_video_queue.
Not exposing this makes encode-only usecases not functional,
eg. SteamVR Link.
Signed-off-by: Joshua Ashton <joshua@froggi.es>