BSSGP_Emulation: Fix automatic BVC flow control ACK in SGSN role

This code had been intended to be used, but commented out, and
never really been completed or tested.

Change-Id: Iaa573219548f2a6a2eb13408fec65c55f9e88ddb
diff --git a/library/BSSGP_Emulation.ttcn b/library/BSSGP_Emulation.ttcn
index 06e4733..c7766dc 100644
--- a/library/BSSGP_Emulation.ttcn
+++ b/library/BSSGP_Emulation.ttcn
@@ -496,12 +496,13 @@
 	}
 
 	/* simply acknowledge all Flow Control Messages */
-/*
-	[g_cfg.sgsn_role] BSCP.receive(f_BnsUdInd(t_BVC_FC_BVC), g_cfg.bvci) {
-		BSCP.send(f_BnsUdReq(t_BVC_FC_BVC_ACK), g_cfg.bvci);
+	[g_cfg.sgsn_role] BSCP.receive(f_BnsUdInd(tr_BVC_FC_BVC, g_cfg.bvci)) -> value udi {
+		var OCT1 tag := udi.bssgp.pDU_BSSGP_FLOW_CONTROL_BVC.tag.unstructured_Value;
+		BSCP.send(f_BnsUdReq(t_BVC_FC_BVC_ACK(tag), g_cfg.bvci));
 	}
-	[g_cfg.sgsn_role] BSCP.receive(f_BnsUdInd(t_BVC_FC_MS), g_cfg.bvci) {
-		BSCP.send(f_BnsUdReq(t_BVC_FC_MS_ACK), g_cfg.bvci);
+/*
+	[g_cfg.sgsn_role] BSCP.receive(f_BnsUdInd(t_BVC_FC_MS, g_cfg.bvci)) {
+		BSCP.send(f_BnsUdReq(t_BVC_FC_MS_ACK, g_cfg.bvci));
 	}
 */