xfs: drop dop param from xfs_defer_op_type ->finish_item() callback

The dfops infrastructure ->finish_item() callback passes the
transaction and dfops as separate parameters. Since dfops is always
part of a transaction, the latter parameter is no longer necessary.
Remove it from the various callbacks.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>