pmdomain: core: Restore behaviour for disabling unused PM domains

Recent changes to genpd prevents those PM domains being powered-on during
initialization from being powered-off during the boot sequence. Based upon
whether CONFIG_PM_CONFIG_PM_GENERIC_DOMAINS_OF is set of not, genpd relies
on the sync_state mechanism or the genpd_power_off_unused() (which is a
late_initcall_sync), to understand when it's okay to allow these PM domains
to be powered-off.

This new behaviour in genpd has lead to problems on different platforms.
Let's therefore restore the behavior of genpd_power_off_unused().
Moreover, let's introduce GENPD_FLAG_NO_STAY_ON, to allow genpd OF
providers to opt-out from the new behaviour.

Link: https://lore.kernel.org/all/20250701114733.636510-1-ulf.hansson@linaro.org/


Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/all/20250902-rk3576-lockup-regression-v1-1-c4a0c9daeb00@collabora.com/


Reported-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Fixes: 0e789b49 ("pmdomain: core: Leave powered-on genpds on until sync_state")
Fixes: 13a4b7fb ("pmdomain: core: Leave powered-on genpds on until late_initcall_sync")
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>