net/mlx5: E-switch, Avoid function change handler for non ECPF

for non ECPF eswitch manager function, vports are already
enabled/disabled when eswitch is enabled/disabled respectively.
Simplify function change handler for such eswitch manager function.

Therefore, ECPF is the only one which remains PF/VF function change
handler.

Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>