BTS_Tests: run TCH and SACCH loops in f_TC_speech_osmux()

I forgot to update this function in [1].  Let's make it consistent with
the f_TC_speech_rtp().  More details can be found in the linked patch.

Change-Id: I8c2f8bb4cc4b44378af5536893bc73fde368b3fe
Related: [1] Ifb69669b75df5b390d7056cefaf0ef1df69d9bd4
diff --git a/bts/BTS_Tests.ttcn b/bts/BTS_Tests.ttcn
index 7691187..3433666 100644
--- a/bts/BTS_Tests.ttcn
+++ b/bts/BTS_Tests.ttcn
@@ -8465,6 +8465,8 @@
 									   amr_cmr := amr_ft);
 	Tu.start(2.0);
 	alt {
+	[] as_l1_tch_loop();
+	[] as_l1_sacch();
 	[] OsmuxEM_DATA.receive(osmux_pdu_exp) -> value osmux_pdu {
 		var boolean matched := false;
 		for (var integer i := 0; i < osmux_pdu.osmux_amr.header.ctr + 1; i := i + 1) {