net/mlx5: Add VDPA interface type to supported enumerations

VDPA is a new interface that will be added in subsequent patches. It
uses mlx5 core devices and resources. Add an interface type for it.

Signed-off-by: Eli Cohen <eli@mellanox.com>
Reviewed-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>