xfs: substitute spaces with tabs

Inside xfs_attr_shortform_list removes spaces at the beginnig of the line
and replaces with tabs.
Issue found by checkpatch.

ERROR: code indent should use tabs where possible

Signed-off-by: Thomas Bianchi <thomas.bianchi8@gmail.com>
Reviewed-by: Bill O'Donnell <billodo@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>