soc: rockchip: power-domain: use pm_genpd_remove in error cleanup

The newly introduced pm_genpd_remove reverts the initialization done
by pm_genpd_init and is necessary in the error path of the rockchip
power-domain driver.

Without it the driver will in the error case cleanup the devm-allocated
structures including the elements referenced in the gpd_list thus making
deactivation of unused domains (and probably later genpd accesses as
well) fail by accessing invalid pointers.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>