Audio V4: setMode VTS incorrectly assume 0 was invalid

Thus the test was always incorrectly failing.
Also improve the test error messages.

Bug: 77307068
Test: VtsHalAudioV4_0TargetTest
Change-Id: I95db94ed99f7ca32af35422e36a95084e72279d8
Signed-off-by: Kevin Rocard <krocard@google.com>