[MERGED] pmdomain: rockchip: reduce indentation in rockchip_pd_power

Rework the logic, so that the function exits early when the
power domain state is already correct to reduce code indentation.

No functional change intended.

Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Adrian Larumbe <adrian.larumbe@collabora.com> # On Rock 5B
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>