net: dsa: add port fdb dump

Dumping a DSA port's FDB entries is not specific to a DSA slave, so add
a dsa_port_fdb_dump function, similarly to dsa_port_fdb_add and
dsa_port_fdb_del.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index f616b34..9803952 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -128,6 +128,7 @@ int dsa_port_fdb_add(struct dsa_port *dp, const unsigned char *addr,
 		     u16 vid);
 int dsa_port_fdb_del(struct dsa_port *dp, const unsigned char *addr,
 		     u16 vid);
+int dsa_port_fdb_dump(struct dsa_port *dp, dsa_fdb_dump_cb_t *cb, void *data);
 int dsa_port_mdb_add(struct dsa_port *dp,
 		     const struct switchdev_obj_port_mdb *mdb,
 		     struct switchdev_trans *trans);