The Kconfig option belongs closer to the corresponding implementation,
hence let's move it from the soc subsystem to the pmdomain subsystem.

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>