BSC_Tests: fix TC_ciph_mode_a5_{0,1,3}

The helper function f_tc_ciph_mode_a5(), thich performs all of the
three tests currently disables the ASSIGNMENT COMMAND since due to
a bug in OsmoBSC a MODE MODIFY would be attempted by the BSC,
causing the testcase to fail.

The problem in OsmoBSC is now fixed and the ASSIGNMENT COMMAND can
be re-enabled again for this test. However, the test function
includes and expects an AoIP transport layer address, which is
not included for signalling assignments.

- Make sure no AoIP transport identifier is included in ths
  ASSIGNMENT COMMAND

- Do not expect an AoIP transport identifier in the
  ASSIGNMENT COMPLETE from the BSC

- Re-Enable the generation of the ASSIGNMENT COMMAND

Change-Id: Ib39d7dd2d1b3665570d7b287e431d10111316437
Closes: OS#2936
diff --git a/bsc/BSC_Tests.ttcn b/bsc/BSC_Tests.ttcn
index 58f2704..0da0a59 100644
--- a/bsc/BSC_Tests.ttcn
+++ b/bsc/BSC_Tests.ttcn
@@ -1473,10 +1473,12 @@
 	var template PDU_BSSAP exp_compl := f_gen_exp_compl();
 	var PDU_BSSAP ass_cmd := f_gen_ass_req();
 	ass_cmd.pdu.bssmap.assignmentRequest.channelType := valueof(ts_BSSMAP_IE_ChannelTypeSIGNAL);
+	ass_cmd.pdu.bssmap.assignmentRequest.circuitIdentityCode := omit;
+	ass_cmd.pdu.bssmap.assignmentRequest.aoIPTransportLayer := omit;
+	exp_compl.pdu.bssmap.assignmentComplete.circuitIdentityCode := omit;
+	exp_compl.pdu.bssmap.assignmentComplete.aoIPTransportLayer := omit;
 
-	// Disable generation of ASSIGNMENT CMD, as OsmoBSC currently performs MODE MODFIY sign->sign (OS#2936)
-	//f_establish_fully(ass_cmd, exp_compl);
-	f_establish_fully(omit, exp_compl);
+	f_establish_fully(ass_cmd, exp_compl);
 }
 testcase TC_ciph_mode_a5_0() runs on test_CT {
 	var MSC_ConnHdlr vc_conn;