net/mlx5: Expose device definitions for object events

Expose an extra device definitions for objects events.

It includes: object_type values for legacy objects and generic data
header for any other object.

Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>