RDMA/mlx5: Fix type assignment for ICM DM

We should hold the UAPI DM type in the base struct and not the internal
mlx5 type.

Fixes: 251b9d78 ("RDMA/mlx5: Re-organize the DM code")
Link: https://lore.kernel.org/r/58dedbd5c132660f808e59166d434e2eaa6ecf7a.1618753425.git.leonro@nvidia.com


Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>