arm64: dts: rockchip: describe Gru/Kevin OPPs + CPU regulators

Used for Gru/Kevin only, as they're the only ones which have a described
CPU regulator. Also, I'm not sure we've validated this table non-Gru
boards.

At the same time, partially describe PWM regulators for Gru, so cpufreq
doesn't think it can crank up the clock speed without changing the
voltage. However, we don't yet have the DT bindings to fully describe
the Over Voltage Protection (OVP) circuits on these boards. Without that
description, we might end up changing the voltage too much, too fast.

Add the pwm-regulator descriptions and associate the CPU OPPs, but leave
them disabled.

Signed-off-by: Brian Norris <briannorris@chromium.org>
[shared gru/kevin parts on a gru device]
Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
[with a bit of reordering]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>