bsc: Start creating 08.08 like API

The 08.08 API will interface with the internal BSC code and it is
the boundary between MSC and BSC. So nothing that calls the BSC
functionality should know about lchan or such.
diff --git a/openbsc/src/gsm_04_11.c b/openbsc/src/gsm_04_11.c
index 40b257d..b835679 100644
--- a/openbsc/src/gsm_04_11.c
+++ b/openbsc/src/gsm_04_11.c
@@ -122,16 +122,11 @@
 				   "GSM 04.11");
 }
 
-static int gsm411_sendmsg(struct msgb *msg, u_int8_t link_id)
+static int gsm411_sendmsg(struct gsm_subscriber_connection *conn, struct msgb *msg, u_int8_t link_id)
 {
-	if (msg->lchan)
-		msg->trx = msg->lchan->ts->trx;
-
-	msg->l3h = msg->data;
-
 	DEBUGP(DSMS, "GSM4.11 TX %s\n", hexdump(msg->data, msg->len));
-
-	return rsl_data_request(msg, link_id);
+	msg->l3h = msg->data;
+	return gsm0808_submit_dtap(conn, msg, link_id);
 }
 
 /* SMC TC1* is expired */
@@ -155,9 +150,6 @@
 	gh->proto_discr = trans->protocol | (trans->transaction_id<<4);
 	gh->msg_type = msg_type;
 
-	/* assign the outgoing lchan */
-	msg->lchan = trans->conn->lchan;
-
 	/* mobile originating */
 	switch (gh->msg_type) {
 	case GSM411_MT_CP_DATA:
@@ -180,7 +172,7 @@
 
 	DEBUGPC(DSMS, "trans=%x\n", trans->transaction_id);
 
-	return gsm411_sendmsg(msg, trans->sms.link_id);
+	return gsm411_sendmsg(trans->conn, msg, trans->sms.link_id);
 }
 
 /* Prefix msg with a RP-DATA header and send as CP-DATA */