ARM: tegra: Add entries for cpufreq on Tegra124

The Tegra124 cpufreq driver relies on certain clocks being present
in the /cpus/cpu@0 node.

Signed-off-by: Tuomas Tynkkynen <ttynkkynen@nvidia.com>
Signed-off-by: Mikko Perttunen <mikko.perttunen@kapsi.fi>
Signed-off-by: Thierry Reding <treding@nvidia.com>