shared/289: do not special-case ext3

shared/289: do not special-case ext3

Commit "3574531 xfstests: count journal size in test 289" makes ext3 a
special case, but now it's not the case anymore after kernel commit

2046fd1 ext3: Count journal as bsddf overhead in ext3_statfs

So just remove the special case, now test passes on both ext3 and ext4,
also ext3 driven by ext4 module.

Signed-off-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>