net/mlx5: Remove initial segmentation duplicate definitions

Device definitions belong in mlx5_ifc, remove the duplicates in
mlx5_core.h.

Signed-off-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Jianbo Liu <jianbol@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>