arm64: dts: mediatek: add mt6357 device-tree

This new device-tree add the regulators, rtc and keys support
for the MT6357 PMIC.

Signed-off-by: Fabien Parent <fparent@baylibre.com>
Signed-off-by: Alexandre Mergnat <amergnat@baylibre.com>
Link: https://lore.kernel.org/r/20230203-evk-board-support-v3-5-0003e80e0095@baylibre.com


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