Audio HAL VTS: getDevice() == NONE => not supported

getDevice does not return a Result, thus it can not return NOT_SUPPORTED.
Consider NONE as not supported.

Test: vts-tradefed run vts --module VtsHalAudioV2_0Target
Test: call/play music/record/video...
Bug: 36311550
Change-Id: I3b6f7a1fbc1d1535faf549f5b031461cb39d1722
Signed-off-by: Kevin Rocard <krocard@google.com>