arm64: dts: rockchip: drop out-of-tree properties from rk3399-ficus regulator

The pwm-regulator for vdd_log uses additional unreviewed properties in the
vendor kernel, which slipped in with the devicetree.
As written, they are unreviewed and unused in all mainline implementations
so drop them again.

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