arm64: dts: mediatek: mt8188: Add support for Mali GPU on Panfrost

Add the necessary OPP table for the GPU and also add a GPU node
to enable support for the Valhall-JM G57 MC3 found on this SoC,
using the Panfrost driver.

Link: https://lore.kernel.org/r/20240527093908.97574-6-angelogioacchino.delregno@collabora.com


Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>