vapostproc, vadeinterlace: misc fixes
vapostproc, vadeinterlace: don't transform caps if no intersection.
If caps to transform don't intersect with those supported by the VA
filter (VAEntrypointVideoProc) then return them as is, because only
pass-through mode is the only possibility.
vapostproc: Append featured caps rather than merge.
So it would be possible to honor upstream preference.
vapostproc: Remove dead code.
va: filter: Validate input parameter in internal function.
va: allocator: log drm modifier