[RTNETLINK]: Don't return error on no-metrics.

Instead just cancel the nested attribute and return 0.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index eeff0b2..8f22549 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -202,8 +202,10 @@
 		}
 	}
 
-	if (!valid)
-		goto nla_put_failure;
+	if (!valid) {
+		nla_nest_cancel(skb, mx);
+		return 0;
+	}
 
 	return nla_nest_end(skb, mx);