Bluetooth: Align the audio proto definition with Google style guide

Respect the guide:
- enum values should be named using CAPITALS_WITH_UNDERSCORES.
- The first value in an enum must have a name including ALL,  ANY, AUTO,
AUTOMATIC, DEFAULT, EMPTY, INVALID, NADA, NIL, NO, NONE, NORMAL,
NOT_SET, NO_ERROR, NULL, OTHER, UNDEFINED, UNINITIALIZED, UNKNOWN,
UNRESOLVED, UNSET, UNSPECIFIED, UNSUPPORTED as a substring

BUG=b:376787697
TEST=None

Change-Id: I9860de9de2df15539896b8b8793f6fb26ef8b538
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/chameleon/+/5982232
Commit-Queue: Yun-hao Chung <howardchung@chromium.org>
Tested-by: Yun-hao Chung <howardchung@chromium.org>
Reviewed-by: John Lai <johnlai@google.com>