ARM: dts: rockchip: Use the GPU to cool CPU thermal zone of veyron mickey

On rk3288 the CPU and GPU temperatures are correlated. Limit the GPU
frequency on veyron mickey to 400 MHz for CPU temperatures >= 65°C
and to 300 MHz for CPU temperatures >= 85°C.

This matches the configuration of the downstream Chrome OS 3.14 kernel,
the 'official' kernel for mickey.

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