leaudio: Remove hidden requirement for the sample frequency

This is old code which is not valid anymore and blocks other frequencies
than 16kHz and 48kHz
Bug: 224933710
Test: atest bluetooth_le_audio_test
Sponsor: @jpawlowski

Change-Id: I83468115f882f4a1dd384b599ec4eeceb66e6979
(cherry picked from commit 96f76a86)