bts: Update towards most recent "laforge/trx" branch

The existing BTS testing code was based on a ~1 week old version
of trxcon+fake_trx from osmocom-bb.git fixeria/trx branch, which
has meanwhile evolved:

* port number change for TRX protocol
* FAKE_TIMING -> FAKE_TOA
* we can now expect responses to our UDP control commands

Let's adapt the testsuite to those changes

Change-Id: I6d0122202e5d23308421e76b75e608d206aab56e
diff --git a/bts/BTS_Tests.ttcn b/bts/BTS_Tests.ttcn
index be9b4cc..af28396 100644
--- a/bts/BTS_Tests.ttcn
+++ b/bts/BTS_Tests.ttcn
@@ -45,7 +45,7 @@
 	charstring mp_rsl_ip := "127.0.0.2";
 	integer mp_rsl_port := 3003;
 	integer mp_trx0_arfcn := 871;
-	integer mp_bb_trxc_port := 5704;
+	integer mp_bb_trxc_port := 6701;
 	charstring mp_pcu_socket := PCU_SOCK_DEFAULT;
 }
 
@@ -266,7 +266,7 @@
 
 	/* start with a default moderate timing offset equalling TA=2 */
 	f_main_trxc_connect();
-	BB_TRXC.send(ts_TRXC_Send(g_bb_trxc_conn_id, ts_TRXC_FAKE_TIMING(2*256)));
+	f_TRXC_transceive(BB_TRXC, g_bb_trxc_conn_id, valueof(ts_TRXC_FAKE_TIMING(2*256)));
 }
 
 /* Attach L1CTL to master test_CT (classic tests, non-handler mode) */
@@ -323,11 +323,11 @@
 }
 
 private function f_trxc_fake_rssi(uint8_t rssi) runs on ConnHdlr {
-	BB_TRXC.send(ts_TRXC_Send(g_bb_trxc_conn_id, ts_TRXC_FAKE_RSSI(rssi))); 
+	f_TRXC_transceive(BB_TRXC, g_bb_trxc_conn_id, valueof(ts_TRXC_FAKE_RSSI(rssi)));
 }
 
 private function f_trx_fake_toffs256(int16_t toffs256) runs on ConnHdlr {
-	BB_TRXC.send(ts_TRXC_Send(g_bb_trxc_conn_id, ts_TRXC_FAKE_TIMING(toffs256))); 
+	f_TRXC_transceive(BB_TRXC, g_bb_trxc_conn_id, valueof(ts_TRXC_FAKE_TIMING(toffs256)));
 }
 
 /* first function started in ConnHdlr component */
@@ -632,7 +632,7 @@
 
 private function f_rach_toffs(int16_t toffs256, boolean expect_pass) runs on test_CT {
 	/* tell fake_trx to use a given timing offset for all bursts */
-	BB_TRXC.send(ts_TRXC_Send(g_bb_trxc_conn_id, ts_TRXC_FAKE_TIMING(toffs256)));
+	f_TRXC_transceive(BB_TRXC, g_bb_trxc_conn_id, valueof(ts_TRXC_FAKE_TIMING(toffs256)));
 	f_sleep(0.5);
 
 	/* Transmit RACH request + wait for confirmation */