bsc: implement ttcn API and cfg for A5/4

Implement tools for OsmoBSC a5/4 support testing:

- in f_cipher_mode() and f_check_chan_act(), expect Kc128 key as
  appropriate, using recently added g_pars.encr.enc_kc128
- osmo-bsc.cfg: allow a5/4

Related: SYS#5324
Change-Id: Ifa48a8498dde7d04fb29f497013bdb5a1e5f3597
diff --git a/bsc/BSC_Tests.ttcn b/bsc/BSC_Tests.ttcn
index 719fce6..a2a7804 100644
--- a/bsc/BSC_Tests.ttcn
+++ b/bsc/BSC_Tests.ttcn
@@ -3461,7 +3461,7 @@
 	f_init(1, true);
 	f_sleep(1.0);
 
-	pars.encr := valueof(t_EncrParams('20'O, f_rnd_octstring(8)));
+	pars.encr := valueof(t_EncrParams('20'O, f_rnd_octstring(8), f_rnd_octstring(16)));
 	vc_conn := f_start_handler(refers(f_TC_assignment_a5_not_sup), pars);
 	vc_conn.done;
 	f_shutdown_helper();