Audio hal VTS: pretty print AudioDevice and ChannelMask

This eases the debuging of failing tests.
Also print hex value of the enums as well of their literal values.

Test: run the test on target
Bug: 34170075
Change-Id: Iea1d7d2269e0e5b413240aaa905daae755846e74
Signed-off-by: Kevin Rocard <krocard@google.com>