xfs: use ->t_dfops for all xfs_bmapi_write() callers

Attach ->t_dfops for all remaining callers of xfs_bmapi_write().
This prepares the latter to no longer require a separate dfops
parameter.

Note that xfs_symlink() already uses ->t_dfops. Fix up the local
references for consistency.

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>