net/mlx5: DR, Use the new HW specific STE infrastructure

Split the STE builders functionality into the common part and
device-specific part. All the device-specific part (with 'v0' in
the function names) is accessed through the STE context structure.

Subsequent patches will have the device-specific logic moved to a
separate file.

Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>