Explain the thermal bindings now that the thermal IP is described being
inside of a system controller. Add a reference to the thermal-zone node.
Signed-off-by: NMiquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NEduardo Valentin <edubezval@gmail.com>