net: dsa: microchip: remove unused private members

Private structure members live_ports, on_ports, rx_ports, tx_ports are
initialized but not used anywhere. Let's remove them.

Suggested-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>