xfs: fix sparse reported log CRC endian issue

Not a bug as such, just warning noise from the xlog_cksum()
returning a __be32 type when it should be returning a __le32 type.

On Wed, Nov 28, 2012 at 08:30:59AM -0500, Christoph Hellwig wrote:
> But why are we storing the crc field little endian while all other on
> disk formats are big endian? (And yes I realize it might as well have
> been me who did that back in the idea, but I still have no idea why)

Because the CRC always returns the calcuation LE format, even on BE
systems. So rather than always having to byte swap it everywhere and
have all the force casts and anootations for sparse, it seems simpler to
just make it a __le32 everywhere....

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>