mgw: osmux: Fix conn watchdog timeout not updated

It is currently done upon receival of RTP packets in rx_rtp for pure RTP
conns, but nothing similar is done for Osmux conns, which eventually
trigger a connection time out.

Change-Id: Id592d7db7b9399a497176e0d28cc826b3bce48c0
diff --git a/src/libosmo-mgcp/mgcp_osmux.c b/src/libosmo-mgcp/mgcp_osmux.c
index 02e31bb..9a3c950 100644
--- a/src/libosmo-mgcp/mgcp_osmux.c
+++ b/src/libosmo-mgcp/mgcp_osmux.c
@@ -390,6 +390,8 @@
 			goto out;
 		}
 
+		mgcp_conn_watchdog_kick(conn_src->conn);
+
 		/*conn_dst = mgcp_find_dst_conn(conn_src->conn);
 		if (!conn_dst) {
 			LOGP(DLMGCP, LOGL_ERROR,