net: lan966x: Add vlan support.

Extend the driver to support vlan filtering  by implementing the
switchdev calls SWITCHDEV_OBJ_ID_PORT_VLAN,
SWITCHDEV_ATTR_ID_BRIDGE_VLAN_FILTERING

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>