RSL_Emulation: Handle ID_ACK event in BSC role

In I483ddd45c1cf631a5a9d8f862b6ca728b38bdc14 we introduced code
that makes the IPA_Emulation code to emut an ASP_IPA_EVENT_ID_ACK
[also] to the RSL port, irrespective of client/server status.

However, RSL_Emulation only handled this event in the BTS role
for BSC testing, but not in in the BSC role for BTS testing.

Change-Id: I99a5c58ea8d1e74b2ad51aed23009af6322a1007
diff --git a/library/RSL_Emulation.ttcn b/library/RSL_Emulation.ttcn
index 3ad062b..3634373 100644
--- a/library/RSL_Emulation.ttcn
+++ b/library/RSL_Emulation.ttcn
@@ -350,6 +350,7 @@
 		[bts_role] IPA_PT.receive(ASP_IPA_Event:{up_down := ASP_IPA_EVENT_ID_ACK}) {
 			IPA_PT.send(ts_ASP_RSL_UD(IPAC_PROTO_RSL_TRX0,ts_RSL_PAGING_LOAD_IND(23)));
 			}
+		[not bts_role] IPA_PT.receive(ASP_IPA_Event:{up_down := ASP_IPA_EVENT_ID_ACK}) { }
 		[bts_role] IPA_PT.receive(tr_RSL(tr_RSL_IMM_ASSIGN)) -> value rx_rsl {
 			var GsmRrMessage rr;
 			var OCT1 ra;