sgsn: add statistics counter for GPRS and PDP packets

Changing the test to allow still allocated block from the rate
counters.

Change-Id: Ie30e4c3084ee3a138d6b39bb5000234ac814e65f
diff --git a/openbsc/src/gprs/sgsn_main.c b/openbsc/src/gprs/sgsn_main.c
index 4475136..52fc985 100644
--- a/openbsc/src/gprs/sgsn_main.c
+++ b/openbsc/src/gprs/sgsn_main.c
@@ -342,6 +342,7 @@
 	bssgp_nsi = sgsn_inst.cfg.nsi = sgsn_nsi;
 
 	gprs_llc_init("/usr/local/lib/osmocom/crypt/");
+	sgsn_rate_ctr_init();
 	sgsn_inst_init();
 
 	gprs_ns_vty_init(bssgp_nsi);