BSC_Tests: Fix test case TC_err_84_unknown

The test cases used UPLINK RELEASE message as test for an unspported
message. This message is supported and does not trigger the expected RR
STATUS message. The fix uses the unsupported DTM ASSIGNMENT FAILURE
message.

To have the DTM ASSIGNMENT FAILE, it is added to
library/L3_Templates.ttcn.

Change-Id: I35877574cf4459332229e3b941918bc0a23b939f
diff --git a/bsc/BSC_Tests.ttcn b/bsc/BSC_Tests.ttcn
index a9cfa03..f2f7f5b 100644
--- a/bsc/BSC_Tests.ttcn
+++ b/bsc/BSC_Tests.ttcn
@@ -5656,10 +5656,9 @@
 	f_shutdown_helper();
 }
 
-
 /* 24.008 8.4 Unknown message must trigger RR STATUS */
 private function f_tc_err_84_unknown_msg(charstring id) runs on MSC_ConnHdlr {
-	f_est_single_l3(ts_RRM_UL_REL('00'O));
+	f_est_single_l3(ts_RRM_DTM_ASS_FAIL('00'O));
 	timer T := 3.0
 	alt {
 	[] RSL.receive(tr_RSL_DATA_REQ(g_chan_nr, ?, decmatch tr_RRM_RR_STATUS)) {