pmdomain: mediatek: Add support for RTFF Hardware in MT8196/MT6991

pmdomain: mediatek: Add support for RTFF Hardware in MT8196/MT6991

New generation SoCs use a new RTFF Hardware to save power during
operation of various IPs, other than managing isolation of the
internal buck converters during powerup/down of power domains.

Since some of the power domains need different RTFF handling, add
a new scpys_rtff_type enumeration and hold the value for each
power domain in struct scpsys_domain_data.

If RTFF HW is available, the RTFF additional power sequences are
handled in scpsys_ctl_pwrseq_{on,off}().

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/20250805074746.29457-9-angelogioacchino.delregno@collabora.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>