ARM: dts: rockchip: update rk3288-veyron cpu operating points

The generic operating points specified in rk3288.dtsi are specified by
Rockchip as conservative and for all cases.

In contrast the Veyron ChromeOS devices are supposed to use a special
chip variant often called rk3288-c and use different operating points
in their kernel also including a higher max frequency.

So override the operating points for veyron devices.

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