Fix handling of qdis without options

Some qdisc like htb want the parse_qopt to be called even if no options
present. Fixes regression caused by:

e9e78b0d is the first bad commit
commit e9e78b0d
Author: Stephen Hemminger <stephen@networkplumber.org>
Date:   Mon Aug 26 08:41:19 2013 -0700

    tc: allow qdisc without options

tc/tc_qdisc.c

@@ -137,15 +137,16 @@ static int tc_qdisc_modify(int cmd, unsigned flags, int argc, char **argv)
 	if (est.ewma_log)
 		addattr_l(&req.n, sizeof(req), TCA_RATE, &est, sizeof(est));
 
-	if (argc) {
-		if (q) {
-			if (!q->parse_qopt) {
-				fprintf(stderr, "qdisc '%s' does not support option parsing\n", k);
-				return -1;
-			}
+	if (q) {
+		if (q->parse_qopt) {
 			if (q->parse_qopt(q, argc, argv, &req.n))
 				return 1;
-		} else {
+		} else if (argc) {
+			fprintf(stderr, "qdisc '%s' does not support option parsing\n", k);
+			return -1;
+		}
+	} else {
+		if (argc) {
 			if (matches(*argv, "help") == 0)
 				usage();