wma_afh: Remove some dead stores.

wma_afh: Remove some dead stores.

scan-build complains with

	Value stored to 'orig_title_bytes' is never read

and similar for orig_artist_bytes and orig_comment_bytes. Indeed,
these variables are only referenced in the if clause but not in the
else clause.

This commit makes them local to the if clause and removes the dead
stores in the else clause..