Move rail gating sequence to happen in nvgpu driver instead of piggybacking on Tegra power gating APIs. Bug 200115454 Change-Id: I8514686c7b137f200021b05ead7157d0883bddc5 Signed-off-by: Terje Bergstrom <tbergstrom@nvidia.com> Reviewed-on: http://git-master/r/761991