frontends/va: Use PIPE_FORMAT_NV12 for YV12/I420
What does this MR do and why?
frontends/va: Use PIPE_FORMAT_NV12 for YV12/I420
There is already code that handles the conversion in vaPutImage/vaGetImage.
This fixes encoding yuv420p format in ffmpeg, which is common when doing software decode -> hardware encode transcoding.