Explicitly include the mandatory IE cn_support in the E1 Setup Request

* this commit is making explicit the mandatory IE cn_support
  in the E1 Setup Request message
* also, init cn_support in E1 Setup Request initial message preparation

openair2/E1AP/e1ap_setup.c

@@ -90,6 +90,9 @@ MessageDef *RCconfig_NR_CU_E1(const E1_t *entity)
     if (*gnbParms[GNB_GNB_NAME_IDX].strptr)
       e1Setup->gNB_cu_up_name = *(gnbParms[GNB_GNB_NAME_IDX].strptr);
 
+    // Only 5GC supported
+    e1Setup->cn_support = cn_support_5GC;
+
     paramdef_t PLMNParams[] = GNBPLMNPARAMS_DESC;
     paramlist_def_t PLMNParamList = {GNB_CONFIG_STRING_PLMN_LIST, NULL, 0};
     /* map parameter checking array instances to parameter definition array instances */