pmdomain: mediatek: Add support for modem power sequences

pmdomain: mediatek: Add support for modem power sequences

Add support for the modem power domains by adding its specific
power sequence in functions scpsys_modem_pwrseq_{on,off}() and
call them if the flag MTK_SCPD_MODEM_PWRSEQ is present.

While at it, since some SoC models need to skip setting/clearing
the PWR_RST_B_BIT, also add a MTK_SCPD_SKIP_RESET_B flag for that.

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/20250805074746.29457-8-angelogioacchino.delregno@collabora.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>