Dont split ID3v23 IPLS frame into ID3v23 TIPL or TMCL based on content just convert to TIPL

ID3v24 has both TIPL (InvolvedPeople) and TMCL (Musicians) fields, but ID3v23 only has one frame to cover both scenarios (IPLS). Previously we tried to convert data in an IPLS frame into either TMCL or TIPL based on content, but it was rather suspect, better to always convert to TIPL when converting v23 to v24.