macvlan: Do not return error when setting the same mac address

The user currently gets an EBUSY error when attempting to set
the mac address on a macvlan device to the same value.

This should really be a no-op as nothing changes.  Catch
the condition and return early.
Signed-off-by: NVladislav Yasevich <vyasevic@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/macvlan.c

@@ -703,6 +703,10 @@ static int macvlan_set_mac_address(struct net_device *dev, void *p)
 	if (!is_valid_ether_addr(addr->sa_data))
 		return -EADDRNOTAVAIL;
 
+	/* If the addresses are the same, this is a no-op */
+	if (ether_addr_equal(dev->dev_addr, addr->sa_data))
+		return 0;
+
 	if (vlan->mode == MACVLAN_MODE_PASSTHRU) {
 		dev_set_mac_address(vlan->lowerdev, addr);
 		return 0;