dt-bindings: i2c: update bindings for MT8192 SoC

Add a DT binding documentation for the MT8192 soc.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Qii Wang <qii.wang@mediatek.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>