AudioMix: add system method for specifying an AudioDeviceInfo
to be used by this mix. This only works for AudioMix
instance with the RENDER route flag.
Previous dynamic policy implementation didn't enforce
mix route flag check, but only supported LOOP_BACK,
so make LOOP_BACK the default.
When a policy gets registered and the registration ID is
set on each mix, for RENDER mixes use the device
address for registration.
Bug 25448664
Change-Id: If5789d84ff4c4c25a6e81ba1513a39916220498a
e8924115f9