ARM: tegra: Add CPU thermal zones to Nyan device-tree

CPU of Nyan Chromebooks is overheating badly because apparently hardware
soctherm controller doesn't work well. Add CPU thermal zones to enable
software thermal control over CPU and fix the overheat trouble.

Tested-by: Thomas Graichen <thomas.graichen@gmail.com> # T124 Nyan Big
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>