Audio V4: Require audio V4 in new devices, optional for upgrades

Upgrading devices are allowed to stay on audio V2,
but can also update to V4.

Bug: 38184704
Test: compile and check V4 can be loaded and functional with lshal
Change-Id: Ib1c8381925837a8402ae535755a0558afcf26f4d
Signed-off-by: Kevin Rocard <krocard@google.com>