ARM: tegra: set vdd_core for Jetson TK1

Program vdd_core for Jetson TK1 to 1V, which is the max safe voltage for
ultra low temperature operations. vdd_cpu and vdd_gpu are already at 1V.

Signed-off-by: Bibek Basu <bbasu@nvidia.com>
(swarren: fixed comments to better match the code)
(swarren: moved board ifdef around data in header, made code generic)
(swarren: fixed typos in commit description)
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>