soc/tegra: regulators: Bump voltages on system reboot

Ensure that SoC voltages are at a level suitable for a system reboot.
This is important for some devices that use CPU reset method for the
rebooting. SoC CPU and core voltages now are be restored to a level
that is suitable for rebooting. This patch fixes hang on reboot on
Asus Transformer TF101, it was also reported as fixing some of reboot
issues on Toshiba AC100.

Reported-by: Nikola Milosavljević <mnidza@outlook.com>
Tested-by: Nikola Milosavljević <mnidza@outlook.com> # TF101
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>