Minor cleanup to go along with matching vhal update

Standardize a few constant names, and a few miscellanious clean ups (but
not net functionality change).

Test:  runtest -x
packages/services/Car/tests/carservice_test/src/com/android/car/test/CarAudioFocusTest.java
(plus 3 others) on Mojave

Change-Id: I70c73f511a63aa714414acaca5bdc4e929946959
Bug: 65384336
5 files changed