soc: mediatek: mtk-pm-domains: Allow probing vreg supply on two MFGs

MediaTek SoCs have multiple MFG power-domains, exclusively used for
the GPU which, in turn, requires external power supplies: make sure
to have the MTK_SCPD_DOMAIN_SUPPLY cap on the two topmost MFGs to
allow voting for regulators on/off upon usage of these power domains.

This also ensures that the SRAM is actually powered and that we're
not relying on the bootloader leaving this supply on when performing
the first (and latter) poweron sequence for these domains' sram.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220623123850.110225-2-angelogioacchino.delregno@collabora.com


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