IB/mlx5: Support scatter to CQE for DC transport type

Scatter to CQE is a HW offload that saves PCI writes by scattering the
payload to the CQE.
This patch extends already existing functionality to support DC
transport type.

Signed-off-by: Yonatan Cohen <yonatanc@mellanox.com>
Reviewed-by: Guy Levi <guyle@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>