net/mlx5: E-Switch, Use vport event handler for vport cleanup

Remove the usage of explicit cleanup function and use existing vport
change handler. Calling vport change handler while vport
is disabled will cleanup the vport resources.

Signed-off-by: Mohamad Haj Yahia <mohamad@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>