stats: replace packet statistic counters with libosmocore rate counters

In struct mgcp_rtp_end one finds unsigned int counters. Those should
be replaced with libosmocore rate counters

- replace packets_rx, octets_rx, packets_tx, octets_tx and
  dropped_packets with libosmocore rate counters.

Change-Id: I47c5c9006df5044e59ddebb895e62adb849d72d5
Related: OS#2517
diff --git a/include/osmocom/mgcp/mgcp_conn.h b/include/osmocom/mgcp/mgcp_conn.h
index e2a423f..3da7334 100644
--- a/include/osmocom/mgcp/mgcp_conn.h
+++ b/include/osmocom/mgcp/mgcp_conn.h
@@ -27,6 +27,17 @@
 #include <osmocom/core/linuxlist.h>
 #include <inttypes.h>
 
+/* RTP connection related counters */
+enum {
+	IN_STREAM_ERR_TSTMP_CTR,
+	OUT_STREAM_ERR_TSTMP_CTR,
+        RTP_PACKETS_RX_CTR,
+        RTP_OCTETS_RX_CTR,
+        RTP_PACKETS_TX_CTR,
+        RTP_OCTETS_TX_CTR,
+        RTP_DROPPED_PACKETS_CTR
+};
+
 struct mgcp_conn *mgcp_conn_alloc(void *ctx, struct mgcp_endpoint *endp,
 				  enum mgcp_conn_type type, char *name);
 struct mgcp_conn *mgcp_conn_get(struct mgcp_endpoint *endp, const char *id);