[XFS] UUID endianess fix. uu_timelow is a 32bit field and needs to be

swapped with be32_to_cpu. 

SGI-PV: 943272
SGI-Modid: xfs-linux-melb:xfs-kern:25232a

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nathan Scott <nathans@sgi.com>