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/gprs/gprs_sgsn.c b/openbsc/src/gprs/gprs_sgsn.c
index 9b11c35..c4dc9d7 100644
--- a/openbsc/src/gprs/gprs_sgsn.c
+++ b/openbsc/src/gprs/gprs_sgsn.c
@@ -25,6 +25,7 @@
 #include <osmocom/core/talloc.h>
 #include <osmocom/core/timer.h>
 #include <osmocom/core/rate_ctr.h>
+#include <osmocom/core/stats.h>
 #include <osmocom/core/backtrace.h>
 #include <osmocom/gprs/gprs_ns.h>
 #include <osmocom/gprs/gprs_bssgp.h>
@@ -71,6 +72,7 @@
 	.group_description = "SGSN MM Context Statistics",
 	.num_ctr = ARRAY_SIZE(mmctx_ctr_description),
 	.ctr_desc = mmctx_ctr_description,
+	.class_id = OSMO_STATS_CLASS_SUBSCRIBER,
 };
 
 static const struct rate_ctr_desc pdpctx_ctr_description[] = {
@@ -85,6 +87,7 @@
 	.group_description = "SGSN PDP Context Statistics",
 	.num_ctr = ARRAY_SIZE(pdpctx_ctr_description),
 	.ctr_desc = pdpctx_ctr_description,
+	.class_id = OSMO_STATS_CLASS_SUBSCRIBER,
 };
 
 static int ra_id_equals(const struct gprs_ra_id *id1,