cpufreq: tegra194: Enable CPUFREQ thermal cooling

Populate the flag CPUFREQ_IS_COOLING_DEV for the Tegra194 CPUFREQ driver
to register it as a cooling device. This enables CPU frequency
throttling for CPUs when the passive trip points are crossed.

Signed-off-by: Yi-Wei Wang <yiweiw@nvidia.com>
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>