pmdomain: mediatek: Convert all SoCs to new style regmap retrieval

Add the bus_prot_blocks handle and declare num_bus_prot_blocks to
allow all of the currently supported AArch64 MediaTek SoCs to use
the new style regmap retrieval in the driver when a new style
devicetree declaring the mediatek,bus-protection phandle(s) in
the main power controller node is found.

Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20250805074746.29457-10-angelogioacchino.delregno@collabora.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>