xfs: remove the never fully implemented UUID fork format

xfs: remove the never fully implemented UUID fork format

Source kernel commit: 42b67dc6ffbf2701cfc578b3e706d560a80b6674

Remove the dead code dealing with the UUID fork format that was never
implemented in Linux (and neither in IRIX as far as I know).

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
[sandeen: use __u8 not u8 for now, adapt xfs_logprint]
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>