Provide basic support for Atheros AR9331 built-in switch. So far it
works as port multiplexer without any hardware offloading support.
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Reviewed-by: NVivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: NOleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>