HSI: Add common DT binding for HSI client devices

Implement and document generic DT bindings for HSI clients.

Signed-off-by: Sebastian Reichel <sre@kernel.org>
Reviewed-by: Pavel Machek <pavel@ucw.cz>
Tested-By: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
diff --git a/include/linux/hsi/hsi.h b/include/linux/hsi/hsi.h
index e20a399..3ec0630 100644
--- a/include/linux/hsi/hsi.h
+++ b/include/linux/hsi/hsi.h
@@ -301,6 +301,17 @@
 int hsi_remove_client(struct device *dev, void *data);
 void hsi_port_unregister_clients(struct hsi_port *port);
 
+#ifdef CONFIG_OF
+void hsi_add_clients_from_dt(struct hsi_port *port,
+			     struct device_node *clients);
+#else
+static inline void hsi_add_clients_from_dt(struct hsi_port *port,
+					   struct device_node *clients)
+{
+	return;
+}
+#endif
+
 static inline void hsi_controller_set_drvdata(struct hsi_controller *hsi,
 								void *data)
 {