bluetooth: Fix Mono/Stereo selection with new codec list

When SBC was selected and user changed Channel mode from Stereo to Mono
the codec type wasn't set properly and the reconfiguration failed.

Bug: 329809288
Flag: EXEMPT - minor refactor
Test: manual - choose SBC and change mode to MONO
Merged-In: If847bab1cc05d8c38a680e87277dd857970b4251
Change-Id: Ie32e3a3aa85f866d504dde7396feacf154a2298b