clk: renesas: rzg2l-cpg: Use GENPD_FLAG_* flags instead of local ones

clk: renesas: rzg2l-cpg: Use GENPD_FLAG_* flags instead of local ones

For watchdog PM domain it is necessary to provide GENPD_FLAG_IRQ_SAFE flag
to be able to power on the watchdog PM domain from atomic context. For
this, adjust the current infrastructure to be able to provide GENPD_FLAG_*
for individual PM domains.

With this, remove the always_on flag from rzg2l_cpg_add_pm_domains() as
it is not necessary anymore.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/20241015164732.4085249-3-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>