[3.0] avcodec: vaapi: fetch profile if not available

The profile might not be available from Open(). It's rare case may happen if our hxxx packetizer is not loaded because the demuxer prevents it (b_packetized = false).

For the current issue, the extra data is set midstream by lavc (and not by our mkv demux).

The 4.0 branch does not need this patch since the VAAPI initialisation is done by lavc.

Thanks Steve for the hint, the same thing is done in directx_va.c.

Co-authored-by: Steve Lhomme robux4@ycbcr.xyz

Fixes #27163 (closed)