PCU_Tests_NS: add missing bound of nrf

Otherwise it will try to use setverdict() with an unbound PDU

Change-Id: Ieafe9017126dd293aad09dad3c8a4180c9c29fa0
diff --git a/pcu/RAW_NS.ttcn b/pcu/RAW_NS.ttcn
index 15a0226..ec484ba 100644
--- a/pcu/RAW_NS.ttcn
+++ b/pcu/RAW_NS.ttcn
@@ -72,7 +72,7 @@
 	log("f_ns_exp() expecting ", exp_rx);
 	alt {
 	[] NSCP[idx].receive(t_NS_RecvFrom(exp_rx)) -> value nrf { }
-	[] NSCP[idx].receive {
+	[] NSCP[idx].receive(t_NS_RecvFrom(?)) -> value nrf {
 		setverdict(fail, "Received unexpected NS: ", nrf);
 		mtc.stop;
 		}