BSC_Tests / RSL_Types: Add enumerated for RSL Cause value

this looks much more human-readable in the logs...

Change-Id: I2bc3de37a3059cc16c6293df45e5c4d620422502
diff --git a/bsc/BSC_Tests.ttcn b/bsc/BSC_Tests.ttcn
index c8016d7..b70c63a 100644
--- a/bsc/BSC_Tests.ttcn
+++ b/bsc/BSC_Tests.ttcn
@@ -377,7 +377,7 @@
 	dt := f_est_dchan('23'O, 23, '00010203040506'O);
 
 	/* simulate CONN FAIL IND */
-	f_ipa_tx(0, ts_RSL_CONN_FAIL_IND(dt.rsl_chan_nr, 0));
+	f_ipa_tx(0, ts_RSL_CONN_FAIL_IND(dt.rsl_chan_nr, RSL_ERR_RADIO_LINK_FAIL));
 	/* TODO: different cause values? */
 
 	/* expect BSC to disable the channel */