atrac3: fix error handling

decode_tonal_components returns a proper AVERROR.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Update for 2.0

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>