[NET_SCHED]: Propagate nla_parse return value

nla_parse() returns more detailed errno codes, propagate them back on
error.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
index be007bb..5a512d4 100644
--- a/net/sched/act_nat.c
+++ b/net/sched/act_nat.c
@@ -45,13 +45,17 @@
 {
 	struct nlattr *tb[TCA_NAT_MAX + 1];
 	struct tc_nat *parm;
-	int ret = 0;
+	int ret = 0, err;
 	struct tcf_nat *p;
 	struct tcf_common *pc;
 
-	if (nla == NULL || nla_parse_nested(tb, TCA_NAT_MAX, nla, NULL) < 0)
+	if (nla == NULL)
 		return -EINVAL;
 
+	err = nla_parse_nested(tb, TCA_NAT_MAX, nla, NULL);
+	if (err < 0)
+		return err;
+
 	if (tb[TCA_NAT_PARMS] == NULL ||
 	    nla_len(tb[TCA_NAT_PARMS]) < sizeof(*parm))
 		return -EINVAL;