aaudio: ignore device updates for UNSPECIFIED

We can get a device change to UNSPECIFIED sometimes
when using a duplicate device.
This can happen when using the Legacy USB HAL and
Usage ALARM or RINGTONE.
It makes no sense so we log an error and ignore it.

Bug: 343006991
Test: see bug for repro steps
Test: atest AAudioTests
Flag: EXEMPT bugfix
Change-Id: I38d1ef0629917d5f0a944996706d6d3c65762171