audio hal: Allow using multiple devices with IStream.get/setDevice

To retain compatibility with existing usages of the "routing"
parameter, IStream.setDevice method must accept multiple devices
(as DeviceAddress). This happens when the patch being created
has multiple sinks.

As a consequence, IStream.getDevices needs to return a vector of
DeviceAddress structs.

Bug: 73240607
Test: make
Change-Id: I77aedeb435988363d30325d045f791f3785c8bb5