tegra: Turn off power detect in board init

tegra: Turn off power detect in board init

Tegra core power rail has leakage voltage around 0.2V while system in
suspend mode. The source of the leakage should be coming from PMC power
detect logic for IO rails power detection.
That can be disabled by writing a '0' to PWR_DET_LATCH followed by writing '0'
to PWR_DET (APBDEV_PMC_PWR_DET_0).

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>