arm64: dts: rockchip: introduce rk3399-op1 operating points

The OP1 is a rk3399 variant used in ChromeOS devices with a slightly
higher frequency rating compared to the regular rk3399, but right now
the only available operating points don't match either variant
with both needing adjustments to actually fit their specs.

Therefore introduce separate operting points, from the ChromeOS kernel,
for the OP1 and use it on Gru devices.

Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>