macvlan: handle set_promiscuity failures

It's quite unlikely that dev_set_promiscuity will fail,
but worth checking just in case.

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/macvlan.c

@@ -337,8 +337,11 @@ static int macvlan_open(struct net_device *dev)
 	int err;
 
 	if (vlan->port->passthru) {
-		if (!(vlan->flags & MACVLAN_FLAG_NOPROMISC))
-			dev_set_promiscuity(lowerdev, 1);
+		if (!(vlan->flags & MACVLAN_FLAG_NOPROMISC)) {
+			err = dev_set_promiscuity(lowerdev, 1);
+			if (err < 0)
+				goto out;
+		}
 		goto hash_add;
 	}