platform/drm-tests: Add MT21 converter to v4l2_stateful_decoder

Add MT21 support to the v4l2_stateful_decoder. We use a software
MT21->NV12 converter because the hardware image processor results in
MD5 mismatches, whereas the software converter does not.

BUG=b:208473735, b:194942425
TEST=Tested by running "v4l2_stateful_decoder -f
vp80-00-comprehensive-005.ivf -a -d" on an elm and comparing the MD5
sums to the those generated by FFMPEG.

Change-Id: I229a47bbfb428801680a642ffb18917b0cdfcbcc
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/drm-tests/+/4484679
Reviewed-by: Nathan Hebert <nhebert@chromium.org>
Reviewed-by: Miguel Casas-Sanchez <mcasas@chromium.org>
Tested-by: Justin Green <greenjustin@google.com>
Reviewed-by: Fritz Koenig <frkoenig@chromium.org>
5 files changed