LeAudio: Improve handling remote device audio locations

With this change we correctly distinguish devices with Mono audio location (0),
from devices which do not support any audio location in a paritcular direction.
This is important for devices which are one direction only - speakers
only or microphone only.

Bug: 388499616
Test: atest bluetooth_le_audio_test bluetooth_le_audio_client_test
Flag: Exempt: day to day fix
Change-Id: Ia1e81140b5fe1998532d0d979c3287a79c76cde9