Don't rely on AppOpsManager in systems without applications

Brillo has no applications, and doesn't run AppOpsManager.  Instead,
services are granted statically configured SELinux permissions at
build time.  Rely on that configuration rather than Android's
dynamically configurable permission model.

Bug: 26936651
Test: Test code on Brillo system is able to connect to the camera.

Change-Id: I84b72a762c2f534c2e1cc6f99ef2003388fb1265