[XFS] remove always-true #ifndef HAVE_FORMAT32 tests

There are several tests for #ifndef HAVE_FORMAT32, but
this is never defined anywhere so it is always the default
behavior; just remove the ifndef goop.

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>