[NET_SCHED]: act_api: fix skb leak in error path

The skb is allocated by the function, so it needs to be freed instead
of trimmed on overrun.

Coverity #614

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 792ce59..2ffa11c 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -707,7 +707,7 @@
 
 rtattr_failure:
 nlmsg_failure:
-	skb_trim(skb, b - skb->data);
+	kfree_skb(skb);
 	return -1;
 }