xfs: trivial sparse fixes for the new scrub code

[darrick: fix broken initializer in xfs_scrub_xattr]

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>