id3v2: prefer TDRC for date over TDRL.

TDRL is what we used as a replacement of TYER, and, according to
http://id3.org/id3v2.4.0-changes :
    TYER - Year
        This frame is replaced by the TDRC frame, 'Recording time'
        [F:4.2.5].
So change TDRL usages to TDRC.

Fixes ticket #3694

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