ARM: dts: rockchip: update the thermal management on rk3288

In some cases the machine radiating is very poor,sometime the temperature
is rising very quickly on heavy loading.So we need have more frequent
polling and better granularity.

Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@collabora.com>