dt-bindings: mediatek: convert pinctrl to yaml

Convert mt65xx, mt6796, mt7622, mt8183 bindings to yaml.

Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210804044033.3047296-3-hsinyi@chromium.org


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>