va: add support for VA_EXPORT_SURFACE_COMPOSED_LAYERS
This adds support for using the
VA_EXPORT_SURFACE_COMPOSED_LAYERS in the
This allows use to export single layer/multi plane formats directly as a YUV format (such as NV12 or YU12). These formats can be imported into gallium as emulated formats (if the driver doesn't support them directly).
The code is similar to what Mark Thompson did for the i915 vaapi driver.
I have tested this using Kodi (with some of my own patches to allow vaapi to be used with the drm prime egl renderer).