soc: rockchip: Mover power-domain driver to the genpd dir

To simplify with maintenance let's move the rockchip power-domain driver to
the new genpd directory. Going forward, patches are intended to be managed
through a separate git tree, according to MAINTAINERS.

Cc: Heiko Stuebner <heiko@sntech.de>
Cc: <linux-rockchip@lists.infradead.org>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/genpd/Makefile

@@ -6,3 +6,4 @@ obj-y					+= bcm/
 obj-y					+= mediatek/
 obj-y					+= qcom/
 obj-y					+= renesas/
+obj-y					+= rockchip/

drivers/genpd/rockchip/Makefile

+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_ROCKCHIP_PM_DOMAINS)	+= pm-domains.o

drivers/soc/rockchip/Makefile

@@ -4,5 +4,4 @@
 #
 obj-$(CONFIG_ROCKCHIP_GRF) += grf.o
 obj-$(CONFIG_ROCKCHIP_IODOMAIN) += io-domain.o
-obj-$(CONFIG_ROCKCHIP_PM_DOMAINS) += pm_domains.o
 obj-$(CONFIG_ROCKCHIP_DTPM) += dtpm.o