ARM: tegra: paz00: Set up voltage regulators for DVFS

Set minimum and maximum voltages, and couple CPU/CORE/RTC regulators.

Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>