net: sched: cls: use nla_nest_cancel instead of nlmsg_trim

To cancel nesting, this function is more convenient.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c
index 8e22718..15d68f2 100644
--- a/net/sched/cls_flow.c
+++ b/net/sched/cls_flow.c
@@ -638,7 +638,7 @@
 	return skb->len;
 
 nla_put_failure:
-	nlmsg_trim(skb, nest);
+	nla_nest_cancel(skb, nest);
 	return -1;
 }