[XFS] Remove final remnants of dirv1 macros and other stuff

SGI-PV: 981498

SGI-Modid: xfs-linux-melb:xfs-kern:32002a

Signed-off-by: Barry Naujok <bnaujok@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>