libpfctl: fix error handling

In two cases we returned E2BIG where it should have been a boolean ('false').

MFC after:	1 week
Sponsored by:	Rubicon Communications, LLC ("Netgate")

lib/libpfctl/libpfctl.c

@@ -1491,7 +1491,7 @@ snl_attr_get_pf_rule_labels(struct snl_state *ss, struct nlattr *nla,
 	bool ret;
 
 	if (l->i >= PF_RULE_MAX_LABEL_COUNT)
-		return (E2BIG);
+		return (false);
 
 	ret = snl_attr_copy_string(ss, nla, (void *)PF_RULE_LABEL_SIZE,
 	    l->labels[l->i]);
@@ -1561,7 +1561,7 @@ snl_attr_get_pf_timeout(struct snl_state *ss, struct nlattr *nla,
 	bool ret;
 
 	if (t->i >= PFTM_MAX)
-		return (E2BIG);
+		return (false);
 
 	ret = snl_attr_get_uint32(ss, nla, NULL, &t->timeouts[t->i]);
 	if (ret)