xfs: pass individual arguments to xfs_bmap_add_extent_hole_real

For the reflink case we'd much rather pass the required arguments than
faking up a struct xfs_bmalloca.

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>