net: mscc: ocelot: introduce conversion helpers between port and netdev

Since the mscc_ocelot_switch_lib is common between a pure switchdev and
a DSA driver, the procedure of retrieving a net_device for a certain
port index differs, as those are registered by their individual
front-ends.

Up to now that has been dealt with by always passing the port index to
the switch library, but now, we're going to need to work with net_device
pointers from the tc-flower offload, for things like indev, or mirred.
It is not desirable to refactor that, so let's make sure that the flower
offload core has the ability to translate between a net_device and a
port index properly.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/dsa/ocelot/seville_vsc9953.c b/drivers/net/dsa/ocelot/seville_vsc9953.c
index 579eb7f..f9b7507 100644
--- a/drivers/net/dsa/ocelot/seville_vsc9953.c
+++ b/drivers/net/dsa/ocelot/seville_vsc9953.c
@@ -1058,6 +1058,8 @@ static u16 vsc9953_wm_enc(u16 value)
 static const struct ocelot_ops vsc9953_ops = {
 	.reset			= vsc9953_reset,
 	.wm_enc			= vsc9953_wm_enc,
+	.port_to_netdev		= felix_port_to_netdev,
+	.netdev_to_port		= felix_netdev_to_port,
 };
 
 static int vsc9953_mdio_bus_alloc(struct ocelot *ocelot)