dt-bindings: ARM: Mediatek: Add mmsys document binding for MT8192

This patch adds the mmsys document binding for MT8192 SoC.

Signed-off-by: Chun-Jie Chen <chun-jie.chen@mediatek.com>
Reviewed-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210726105719.15793-3-chun-jie.chen@mediatek.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>