xfs: replace ATTR_KERNOTIME with XFS_DA_OP_NOTIME

op_flags with the XFS_DA_OP_* flags is the usual place for in-kernel
only flags, so move the notime flag there.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Chandan Rajendra <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>