arm64: dts: mediatek: mt6795: Add pinctrl controller node

Add a node for the pinctrl controller found on MT6795 but without
configuration for any pin, as that's expected to be done in the
machine-specific devicetrees.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220609112303.117928-10-angelogioacchino.delregno@collabora.com


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