hsr: remove unnecessary code in hsr_dev_change_mtu()

In the hsr_dev_change_mtu(), the 'dev' and 'master->dev' pointer are
same. So, the 'master' variable and some code are unnecessary.
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/hsr/hsr_device.c

@@ -125,13 +125,11 @@ int hsr_get_max_mtu(struct hsr_priv *hsr)
 static int hsr_dev_change_mtu(struct net_device *dev, int new_mtu)
 {
 	struct hsr_priv *hsr;
-	struct hsr_port *master;
 
 	hsr = netdev_priv(dev);
-	master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
 
 	if (new_mtu > hsr_get_max_mtu(hsr)) {
-		netdev_info(master->dev, "A HSR master's MTU cannot be greater than the smallest MTU of its slaves minus the HSR Tag length (%d octets).\n",
+		netdev_info(dev, "A HSR master's MTU cannot be greater than the smallest MTU of its slaves minus the HSR Tag length (%d octets).\n",
 			    HSR_HLEN);
 		return -EINVAL;
 	}