arm64: dts: mediatek: mt8395-nio-12l: Add power supplies for CPU/GPU scaling

Add the necessary power supplies to safely enable CPU and GPU frequency
scaling.

Link: https://lore.kernel.org/r/20240409114211.310462-6-angelogioacchino.delregno@collabora.com


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