ARM: dts: NSP: Add Thermal Support

Add thermal support via the ns-thermal driver and create a single
thermal zone for the entire SoC.

Signed-off-by: Jon Mason <jon.mason@broadcom.com>
Acked-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>