thermal: tegra: support hw and sw shutdown

Currently the critical trip points in thermal framework are the only
way to specify a temperature at which HW should shutdown. This is
insufficient for certain platforms which would want an orderly
software shutdown in addition to HW shutdown.

This change support to parse "nvidia, thermtrips" property,
it allows soctherm DT to specify thermtrip temperatures so that
critical trip points framework can be used for doing software
shutdown.

Signed-off-by: Wei Ni <wni@nvidia.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>