LE Audio: accept 24 bit audio from audio framework properly

LC3 encoder expects the 24 bit audio packet in uint32_t.
Audio Frameworks provide 24bit audio in packed format currently.
In LE Audio code, we must accout for potential 24bit inputs.

Bug: 230578655
Test: Switch configuration to 24bit mode, play music
Change-Id: I4bc7aebb7437023114f732866322c026b71bcf56