Audio V4: Remove system only enum values

Some enum values only used by the system were exposed to the vendor for
legacy reason. Remove them.

Bug: 38184704
Test: compile
Change-Id: I78254047a74d08bcdf2d7b285e874dbd497d5407
Merged-In: I78254047a74d08bcdf2d7b285e874dbd497d5407
Cherry-picked from master
Signed-off-by: Kevin Rocard <krocard@google.com>