codec: liba52: fix wrong output size
codec: liba52: fix wrong output size

decoder_NewAudioBuffer expects samples while we gave bytes.

Fixes #17319

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc