cpufreq: tegra194: Add support for Tegra239

Adding support for Tegra239 SoC which has eight cores in
a single cluster. Also, moving num_clusters to SoC data
to avoid over allocating memory for four clusters always.

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>