dt-bindings: display: mediatek: dsc: add yaml for mt8195 SoC binding

1. Add mediatek,dsc.yaml to describe DSC module in details.
2. Add mt8195 SoC binding to mediatek,dsc.yaml.

Signed-off-by: jason-jh.lin <jason-jh.lin@mediatek.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>