arm64: tegra: Enable PWM fan on Jetson Nano

Enable PWM fan and extend CPU thermal zones for monitoring and fan control.
This will trigger the PWM fan on J15 and cool down the system if necessary.

Signed-off-by: Tamás Szűcs <tszucs@protonmail.ch>
Signed-off-by: Thierry Reding <treding@nvidia.com>