[NETLINK]: Use nlmsg_trim() where appropriate

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/act_gact.c

@@ -28,6 +28,7 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/proc_fs.h>
+#include <net/netlink.h>
 #include <net/sock.h>
 #include <net/pkt_sched.h>
 #include <linux/tc_act/tc_gact.h>
@@ -181,7 +182,7 @@ static int tcf_gact_dump(struct sk_buff *skb, struct tc_action *a, int bind, int
 	return skb->len;
 
 rtattr_failure:
-	skb_trim(skb, b - skb->data);
+	nlmsg_trim(skb, b);
 	return -1;
 }