arm64: dts: rockchip: fix the px30-evb power tree

Add the board's pmic (rk809) and hook up the real supplies to their
consumers. This is especially important as cpufreq would otherwise hang
the system when scaling the frequency without adjusting the voltage.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20190917082659.25549-5-heiko@sntech.de