net: dsa: Split up creating/destroying of DSA and CPU ports

Refactor the code to setup a single DSA/CPU port into a function of
its own, and export it, so it can be used by the new binding.

Similarly, refactor the destroy code into a function.  When destroying
the ports, don't put the of node. They should be released at the end
along with the normal ports.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.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 dfa3377..dbea5d9 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -50,6 +50,9 @@
 
 /* dsa.c */
 extern char dsa_driver_version[];
+int dsa_cpu_dsa_setup(struct dsa_switch *ds, struct device *dev,
+		      struct device_node *port_dn, int port);
+void dsa_cpu_dsa_destroy(struct device_node *port_dn);
 
 /* slave.c */
 extern const struct dsa_device_ops notag_netdev_ops;