brillo: Don't even try contacting the camera proxy

This service isn't running, and every time we try, we spend
five seconds retrying to get a reference to a binder that
will never be registered with the service manager.

Bug: 26936651
Test: With this patch, 5 second pauses with logs disappear.

Change-Id: I9cc6b1b616f1b786c3bb4e687b1c742d31424684