tui: properly initialize InfiniBand transport-mode

We need to initialize transport-mode because default value is NULL,
which is not a valid mode.

tui/nmt-page-infiniband.c

@@ -69,6 +69,12 @@ nmt_page_infiniband_constructed (GObject *object)
 		nm_connection_add_setting (conn, nm_setting_infiniband_new ());
 		s_ib = nm_connection_get_setting_infiniband (conn);
 	}
+	/* initialize 'transport-mode' if it is NULL */
+	if (!nm_setting_infiniband_get_transport_mode (s_ib)) {
+		g_object_set (G_OBJECT (s_ib),
+		              NM_SETTING_INFINIBAND_TRANSPORT_MODE, "datagram",
+		              NULL);
+	}
 
 	deventry = nmt_page_device_get_device_entry (NMT_PAGE_DEVICE (object));
 	g_object_bind_property (s_ib, NM_SETTING_INFINIBAND_MAC_ADDRESS,