ip6: fix icmp throttling error index

Type: fix
Change-Id: I57ce42c193fd9408b9d4790482ea76d784148c30
Signed-off-by: Maxime Peim <mpeim@cisco.com>
diff --git a/src/vnet/ip/icmp6.c b/src/vnet/ip/icmp6.c
index b095f67..f93ebce 100644
--- a/src/vnet/ip/icmp6.c
+++ b/src/vnet/ip/icmp6.c
@@ -338,7 +338,7 @@
 
 	  if (throttle_check (&icmp_throttle, thread_index, r0, seed))
 	    {
-	      vlib_error_count (vm, node->node_index, ICMP4_ERROR_DROP, 1);
+	      vlib_error_count (vm, node->node_index, ICMP6_ERROR_DROP, 1);
 	      from += 1;
 	      n_left_from -= 1;
 	      continue;