xfs: remove xfs_btree_cur bmbt dfops field

xfs: remove xfs_btree_cur bmbt dfops field

Source kernel commit: 42b394a92562b464e9ef81954ca93930c037a51b

All assignments of xfs_btree_cur.bc_private.b.dfops originate from
->t_dfops. Replace accesses of the former with the latter and remove
the unnecessary field. This patch does not change behavior.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-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>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>