net: dsa: Make dsa_switch_ops const

Now that we have properly encapsulated and made drivers utilize exported
functions, we can switch dsa_switch_ops to be a annotated with const.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index d43d12c..eea8e01 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -4361,7 +4361,7 @@ static int mv88e6xxx_port_mdb_dump(struct dsa_switch *ds, int port,
 	return err;
 }
 
-static struct dsa_switch_ops mv88e6xxx_switch_ops = {
+static const struct dsa_switch_ops mv88e6xxx_switch_ops = {
 	.probe			= mv88e6xxx_drv_probe,
 	.get_tag_protocol	= mv88e6xxx_get_tag_protocol,
 	.setup			= mv88e6xxx_setup,