net: dsa: Make dsa_master_set_mtu() static

Add the missing static keyword.

Signed-off-by: Andrew Lunn <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/dsa/master.c

···
 	cpu_dp->orig_ethtool_ops = NULL;
 }
 
-void dsa_master_set_mtu(struct net_device *dev, struct dsa_port *cpu_dp)
+static void dsa_master_set_mtu(struct net_device *dev, struct dsa_port *cpu_dp)
 {
 	unsigned int mtu = ETH_DATA_LEN + cpu_dp->tag_ops->overhead;
 	int err;