arm64: tegra: misc fixes to hardwood driver

arm64: tegra: misc fixes to hardwood driver

* Set NS bit when kernel is non-secure
* fix potential race in late_init
* enable hotplug notifier in late_init
* set buf occupied if immediately available
* better debugging print

Change-Id: I7acd736888f05facc559c7c965e20aea6f43060c
Signed-off-by: Peng Du <pdu@nvidia.com>
Reviewed-on: http://git-master/r/432822
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Thomas Cherry <tcherry@nvidia.com>