keep per-BTS stat_items about RACH busy / RACH access percentage

Change-Id: I3ad0cc4866d6210181cbafbab876e8028ad27540
diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h
index 68c95e1..82bd238 100644
--- a/include/osmocom/bsc/gsm_data.h
+++ b/include/osmocom/bsc/gsm_data.h
@@ -1378,6 +1378,8 @@
 enum {
 	BTS_STAT_CHAN_LOAD_AVERAGE,
 	BTS_STAT_T3122,
+	BTS_STAT_RACH_BUSY,
+	BTS_STAT_RACH_ACCESS,
 };
 
 enum {