Revert r6124, the change was just wrong, other formats than MPEG-PS can be
stored in CDXA as well. And the need for a CDXA specific check is questionable.
Also ive ok-ed that patch instead of mans ...
fixes issue287 (psxstr misdetection as MPEG-PS)

Original commit message:
add support for information in CDXA format
patch by Allan Sandfeld Jensen % kde A carewolf P com %
Original thread:
Date: Aug 18, 2006 6:33 PM
Subject: [Ffmpeg-devel] CDXA in libavformat [patch]

Originally committed as revision 11314 to svn://svn.ffmpeg.org/ffmpeg/trunk
