soc/tegra: regulators: Prepare for suspend

Depending on hardware version, Tegra SoC may require a higher voltages
during resume from system suspend, otherwise hardware will crash. Set
SoC voltages to a nominal levels during suspend.

Link: https://lore.kernel.org/all/a8280b5b-7347-8995-c97b-10b798cdf057@gmail.com/


Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>