net/mlx5e: Use the new mlx5 core notifier API

Remove the deprecated mlx5_interface->event mlx5e callback and use new
mlx5 notifier API to subscribe for mlx5 events, handle port change event
as received from FW rather than handling the mlx5 core processed port
change software version event.

Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>