Make torch shutdown by camera usage work properly.

Previously, there were two issues when torch was shut down due to
another camera app being used:
- The service is stopped asynchronously. Work around that by
  shortcutting the torch disable path
- Even after torch shutdown, the periodic refresh may try to enable it
  again. Avoid that by not using the periodic refresh for devices which
  use the camera interface, it's not needed there anyway.

Change-Id: I613c11330875c23c04b7d7339529fb8f1774adcf