soc: mediatek: pm-domains: Add extra sram control

For some power domains like vpu_core on MT8183 whose sram need to do clock
and internal isolation while power on/off sram. We add a cap
"MTK_SCPD_SRAM_ISO" to judge if we need to do the extra sram isolation
control or not.

Signed-off-by: Weiyi Lu <weiyi.lu@mediatek.com>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20201030113622.201188-8-enric.balletbo@collabora.com


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