ARM: dts: sun7i: Add cpu thermal zones to dtsi

The core temperature sensor now supports thermal zones. Add a thermal
zone mapping for the cpus with passive cooling (cpufreq throttling).

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>