video: tegra: host: fix VI regulator race

video: tegra: host: fix VI regulator race

- sometimes regulator_put() from nvhost_vi_deinit() is called
  before regulator_disable() from nvhost_vi_prepare_poweroff()
- this leaves regulator on with no reference to it

- fix this race by moving
  regulator_get() to nvhost_vi_finalize_poweron() and
  regulator_put() to nvhost_vi_prepare_poweroff()

Bug 1398454

Change-Id: I539b543bea73b09ff4713a456654999c7f8280a0
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/330338
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>