arm64: dts: allwinner: h6: Add thermal trip points/cooling map

This enables passive cooling by down-regulating CPU voltage
and frequency.

Signed-off-by: Ondrej Jirman <megous@megous.com>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>