When CONFIG_NET_DSA_LEGACY is n, there is a GCC bulid warning:
drivers/net/dsa/mv88e6xxx/chip.c:4623:13: warning: ‘mv88e6xxx_ports_cmode_init’ defined but not used [-Wunused-function]
static void mv88e6xxx_ports_cmode_init(struct mv88e6xxx_chip *chip)
Let's fix it.

Fixes: ed8fe20205ac ("net: dsa: mv88e6xxx: prevent interrupt storm caused by mv88e6390x_port_set_cmode")
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Vivien Didelot <vivien.didelot@gmail.com> 
Cc: Florian Fainelli <f.fainelli@gmail.com> 
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
---
 drivers/net/dsa/mv88e6xxx/chip.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index e4ad16b2dc38..168d4898c36f 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -4620,14 +4620,6 @@ static int mv88e6xxx_smi_init(struct mv88e6xxx_chip *chip,
 	return 0;
 }
 
-static void mv88e6xxx_ports_cmode_init(struct mv88e6xxx_chip *chip)
-{
-	int i;
-
-	for (i = 0; i < mv88e6xxx_num_ports(chip); i++)
-		chip->ports[i].cmode = MV88E6XXX_PORT_STS_CMODE_INVALID;
-}
-
 static enum dsa_tag_protocol mv88e6xxx_get_tag_protocol(struct dsa_switch *ds,
 							int port)
 {
@@ -4637,6 +4629,14 @@ static enum dsa_tag_protocol mv88e6xxx_get_tag_protocol(struct dsa_switch *ds,
 }
 
 #if IS_ENABLED(CONFIG_NET_DSA_LEGACY)
+static void mv88e6xxx_ports_cmode_init(struct mv88e6xxx_chip *chip)
+{
+	int i;
+
+	for (i = 0; i < mv88e6xxx_num_ports(chip); i++)
+		chip->ports[i].cmode = MV88E6XXX_PORT_STS_CMODE_INVALID;
+}
+
 static const char *mv88e6xxx_drv_probe(struct device *dsa_dev,
 				       struct device *host_dev, int sw_addr,
 				       void **priv)
-- 
2.7.4