dt-bindings: arm: mediatek: mmsys: add support for MT8186

Add "mediatek,mt8186-mmsys" to binding document.

Signed-off-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220301080105.31323-2-rex-bc.chen@mediatek.com


Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>