anv: Adds a workaround for HEVC decoding on some old platforms.

anv: Adds a workaround for HEVC decoding on some old platforms.

HEVC support on Gfx9 is only available on VCS0. So limit the number of video queues
to the first VCS engine instance.

We should be able to query HEVC support from the kernel using the engine query uAPI,
but this appears to be broken : https://gitlab.freedesktop.org/drm/intel/-/issues/8832

When this bug is fixed we should be able to check HEVC support to determine the
correct number of queues.

Closes: mesa/mesa#9172, mesa/mesa#9314
Signed-off-by: Hyunjun Ko <zzoon@igalia.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24065>