xbmc
[linux] allow using VAAPI with DRM PRIME
This is in conjunction with #19140 as it won't work on it's own. I'm PRing it separate to keep review smaller (and because I'm able to as the decoder is separate from the renderer).
This allow using ffmpegs av_hwframe_map to convert AV_PIX_FMT_VAAPI to AV_PIX_FMT_DRM_PRIME. The difference is basically a struct and doesn't require any copying.
This allow us to use the direct-to-plane rendering and EGL render methods for DRM PRIME.
Currently this PR doesn't offer any reason to use DRM PRIME with vaapi over our normal vaapi renderer. However in the future we will be able to activate HDR with VAAPI.
@jernejsk I added a commit to check for m_pFrame->buf[0]. Please check :smiley:
