BSSAP_Adapter: Introduce transport over IPA/SCCPlite

In addition to the existing 3GPP AoIP stacking, allow BSSAP to
run on top of a SCCPlite stacking.  Implement both the server and the
client role for IPA.

Related: OS#2544
Change-Id: Ie844c4de62e0ef5d5c4c366185968211a7f6d676
diff --git a/bsc/BSC_Tests.ttcn b/bsc/BSC_Tests.ttcn
index 8380175..0299026 100644
--- a/bsc/BSC_Tests.ttcn
+++ b/bsc/BSC_Tests.ttcn
@@ -100,6 +100,7 @@
 	charstring mp_test_ip := "127.0.0.1";
 
 	BSSAP_Configuration mp_bssap_cfg := {
+		transport := BSSAP_TRANSPORT_AoIP,
 		sccp_service_type := "mtp3_itu",
 		sctp_addr := { 23905, "127.0.0.1", 2905, "127.0.0.1" },
 		own_pc := 185,