directx_va: only call profile readers if we don't have one

That's how MediaCodec does it. These readers can be wrong so rely on lavc and container values instead.

Fixes #25850 (closed)

(cherry picked from commit a69b492a) (edited) edited:

• the 3.0 branch sets the is_supported later

Signed-off-by: Steve Lhomme robux4@ycbcr.xyz