BluetoothLeAudio: Add MONO location

Due to errata audio location 0x0000 is not "invalid" anymore but
instead "Mono Audio (no specified Audio Location)"

https://www.bluetooth.com/specifications/assigned-numbers/
6.12.1 Audio Location Definitions

Also new Unknown location is added which is used only when Bluetooth is
not available.

Bug: 330847930
Bug: 331139722
Test: mmm packages/modules/Bluetooth

Change-Id: Ibadaee63edd123ba4b31edade524344d6689135e