[Misc] Only create KeyguardStatusBarViewController once inside

NotificationPanelViewController.

The KeyguardStatusBarView never changes, so we don't need to
re-create its controller in NPVController#updateViewControllers.

Fixes: 194181195
Test: atest and manual

Change-Id: If955a8d6167a08bec6e7a7e9e66a2c6a55f68966