fsck.gfs2: fix leaf blocks, don't try to patch the hash table
    
    Before this patch, when we detected a bad leaf block, fsck.gfs2 would
    try to patch the hash table. That's very wrong, because the hash table
    needs to be on nice power-of-two boundaries. This patch changes the
    code so that the hash table is actually repaired.
    
    rhbz#902920