stats: Set class_id in rate_ctr group descriptions

This commit adds the class_id initialiser to all rate_ctr_group_desc
definitions.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/src/libfilter/bsc_msg_acc.c b/openbsc/src/libfilter/bsc_msg_acc.c
index 6258b35..bfc5bdd 100644
--- a/openbsc/src/libfilter/bsc_msg_acc.c
+++ b/openbsc/src/libfilter/bsc_msg_acc.c
@@ -22,6 +22,7 @@
 #include <openbsc/bsc_nat.h>
 
 #include <osmocom/core/rate_ctr.h>
+#include <osmocom/core/stats.h>
 
 #include <string.h>
 
@@ -35,6 +36,7 @@
 	.group_description = "NAT Access-List Statistics",
 	.num_ctr = ARRAY_SIZE(acc_list_ctr_description),
 	.ctr_desc = acc_list_ctr_description,
+	.class_id = OSMO_STATS_CLASS_GLOBAL,
 };