soc: mediatek: pm-domains: Add buck isolation offset and mask to power domain data

Add buck isolation offset and mask to power domain data.

Signed-off-by: Allen-KH Cheng <allen-kh.cheng@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230117032640.13504-2-allen-kh.cheng@mediatek.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>