pcu: TC_sns_add: fix wrong udp port in SNS ADD message

When sending the SNS ADD in the test case the ip/port to add must be different
from the current NSVCs.

Fixes: 90f1974fb0 ("NS_Emulation: Support multiple NS-VC within one NSE (NS-VCG)")

Change-Id: I9bbbf1431468a452df324a7559518496e3eb48e3

pcu/PCU_Tests_SNS.ttcn

@@ -147,7 +147,7 @@ function f_outgoing_sns_add(integer idx_add, uint8_t w_sig := 1, uint8_t w_user
 runs on RAW_NS_CT {
 	log("f_outgoing_sns_add(idx_add=", idx_add, ")");
 	var PDU_NS rx;
-	var NSVCConfiguration nsvc_cfg := g_nsconfig[idx].nsvc[0];
+	var NSVCConfiguration nsvc_cfg := g_nsconfig[idx_add].nsvc[0];
 	if (nsvc_cfg.provider.ip.address_family == AF_INET) {
 		var template (omit) IP4_Elements v4 := { ts_SNS_IPv4(nsvc_cfg.provider.ip.local_ip,
 								     nsvc_cfg.provider.ip.local_udp_port,