cpufreq: tegra124: extend to support Tegra210

Tegra210 uses the same methodology as Tegra124 for CPUFreq controlling
that based on DFLL clock. So extending this driver to support Tegra210.

Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-pm@vger.kernel.org
Signed-off-by: Joseph Lo <josephl@nvidia.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>