iu_client: allow to control the notifications

The iu_client is informing the library user about global event.
In prepration to the tx_iu_release_free() call allow to
disable upstream notificatiosn

Change-Id: Ic93ef6fd54c995405e9c37a5e0c53f81a89850b7
diff --git a/src/iu_client.c b/src/iu_client.c
index ec5290f..38c8a1d 100644
--- a/src/iu_client.c
+++ b/src/iu_client.c
@@ -116,6 +116,9 @@
 	if (!global_iu_event_cb)
 		return 0;
 
+	if (!ue_ctx->notification)
+		return 0;
+
 	return global_iu_event_cb(ue_ctx, type, data);
 }
 
@@ -125,6 +128,7 @@
 
 	ctx->rnc = rnc;
 	ctx->conn_id = conn_id;
+	ctx->notification = true;
 	llist_add(&ctx->list, &ue_conn_ctx_list);
 
 	return ctx;