arm64: dts: rockchip: add #power-domain-cells to power domain nodes

Add #power-domain-cells to power domain nodes, because they
are required by power-domain.yaml

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/20210417112952.8516-9-jbx6244@gmail.com


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