Fix tc stats when using -batch mode

There are two global variables in tc/tc_class.c:
__u32 filter_qdisc;
__u32 filter_classid;

These are not re-initialized for each line received in -batch mode:
class show dev eth0 parent 1: classid 1:1
class show dev eth0 parent 1: classid 1:1
Error: duplicate "classid": "1:1" is the second value.

This patch fixes the issue by initializing the two globals when we
enter print_class().
Signed-off-by: Nigel Kukard <nkukard@lbsd.net>

tc/tc_class.c

@@ -241,6 +241,9 @@ static int tc_class_list(int argc, char **argv)
 	t.tcm_family = AF_UNSPEC;
 	memset(d, 0, sizeof(d));
 
+	filter_qdisc = 0;
+	filter_classid = 0;
+
 	while (argc > 0) {
 		if (strcmp(*argv, "dev") == 0) {
 			NEXT_ARG();