mgcp_client_fsm: switch to MGCP_CONN_RECV_SEND in add_audio()

The change Ie51cc86e90ffeca5b66bcb8f6db0d389241abe57 has replaced the
functions make_crcx_msg_bind() and make_crcx_msg_bind_connect() with
make_crcx_msg() and add_audio(). When a bidirectional connection is
needed, the user calls add_audio() to add the remaining connection
details. Unfortunately add_audio() leaves the conn_mode struct member
unchanged. Which means the connection is still at MGCP_CONN_RECV_ONLY,
which will instruct the MGW not to forward any of the received packets.

- Make sure that conn_mode is set to MGCP_CONN_RECV_SEND when
  add_audio() is called.

Change-Id: Id12de37797de5af5cc447642d2fbb1af7de680df
Closes: OS#3511
diff --git a/src/libosmo-mgcp-client/mgcp_client_fsm.c b/src/libosmo-mgcp-client/mgcp_client_fsm.c
index 0b5a251..5368ec3 100644
--- a/src/libosmo-mgcp-client/mgcp_client_fsm.c
+++ b/src/libosmo-mgcp-client/mgcp_client_fsm.c
@@ -131,6 +131,7 @@
 	mgcp_msg->presence |= MGCP_MSG_PRESENCE_AUDIO_IP | MGCP_MSG_PRESENCE_AUDIO_PORT;
 	mgcp_msg->audio_ip = info->addr;
 	mgcp_msg->audio_port = info->port;
+	mgcp_msg->conn_mode = MGCP_CONN_RECV_SEND;
 }
 
 static struct msgb *make_mdcx_msg(struct mgcp_ctx *mgcp_ctx)