dt-bindings: power: mediatek: Update maintainer list

Update the maintainer list of power controller binding.

Signed-off-by: Tinghan Shen <tinghan.shen@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220729063208.16799-6-tinghan.shen@mediatek.com


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