drm/mediatek: Add DSC support for mediatek-drm

DSC is designed for real-time systems with real-time compression,
transmission, decompression and display.
The DSC standard is a specification of the algorithms used for
compressing and decompressing image display streams, including
the specification of the syntax and semantics of the compressed
video bit stream.

Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20220526102126.19756-2-jason-jh.lin@mediatek.com/
Signed-off-by: jason-jh.lin <jason-jh.lin@mediatek.com>
Acked-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>