mp3_afh: Don't bail out on short files.

mp3_afh: Don't bail out on short files.

It's perfectly OK to have mp3 files which are shorter than two seconds.
For example lexico.com offers mp3 downloads to learn the pronuciation
of single words. These files are often shorter than one second.

The check for short length files predates the git history. Most likely
it was added for no good reason, so drop it.