net: dsa: Make use of devlink port flavour unused

If a port is unused, still create a devlink port for it, but set the
flavour to unused. This allows us to attach devlink regions to the
port, etc.
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Tested-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/dsa2.c

@@ -272,6 +272,15 @@ static int dsa_port_setup(struct dsa_port *dp)
 
 	switch (dp->type) {
 	case DSA_PORT_TYPE_UNUSED:
+		memset(dlp, 0, sizeof(*dlp));
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_UNUSED;
+		devlink_port_attrs_set(dlp, &attrs);
+		err = devlink_port_register(dl, dlp, dp->index);
+		if (err)
+			break;
+
+		devlink_port_registered = true;
+
 		dsa_port_disable(dp);
 		break;
 	case DSA_PORT_TYPE_CPU:
@@ -355,6 +364,7 @@ static void dsa_port_teardown(struct dsa_port *dp)
 
 	switch (dp->type) {
 	case DSA_PORT_TYPE_UNUSED:
+		devlink_port_unregister(dlp);
 		break;
 	case DSA_PORT_TYPE_CPU:
 		dsa_port_disable(dp);