platform: wifi: drop old wifi data when an interface is renamed

Drop the old wifi data when the interface is renamed, otherwise WEXT
methods would use the old name.

https://bugzilla.gnome.org/show_bug.cgi?id=768433

src/platform/wifi/wifi-utils.c

@@ -72,6 +72,22 @@ wifi_utils_init (const char *iface, int ifindex, gboolean check_scan)
 	return ret;
 }
 
+int
+wifi_utils_get_ifindex (WifiData *data)
+{
+	g_return_val_if_fail (data != NULL, -1);
+
+	return data->ifindex;
+}
+
+const char *
+wifi_utils_get_iface (WifiData *data)
+{
+	g_return_val_if_fail (data != NULL, NULL);
+
+	return data->iface;
+}
+
 NMDeviceWifiCapabilities
 wifi_utils_get_caps (WifiData *data)
 {