bsc: fixup for f_TC_refuse_mode_modif_to_vamos

The VTY command changed in the course of development, forgot to update
the test case.

Change-Id: I761b186c19b1307cc15d0bcf6f632b4bb967e254
diff --git a/bsc/BSC_Tests.ttcn b/bsc/BSC_Tests.ttcn
index abcfece..6f603b1 100644
--- a/bsc/BSC_Tests.ttcn
+++ b/bsc/BSC_Tests.ttcn
@@ -8599,7 +8599,7 @@
 
 	f_establish_fully(ass_cmd, exp_compl);
 
-	f_vty_transceive(BSCVTY, "vamos modify first");
+	f_vty_transceive(BSCVTY, "vamos modify lchan 0 0 1 0 tsc 2 3");
 
 	var RSL_Message rsl;