xfs: renumber XBF_WRITE_FAIL

Assining a numerical value that is not close to the flags
defined near by is just asking for conflicts later on.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>