of: make of_device_make_bus_id() static

of_device_make_bus_id() was changed to non-static by commit c6601225
("of/device: Make of_device_make_bus_id() usable by other code") more than
6 years ago, but there are no users of it outside of platform.c.  Make the
function static again.
Signed-off-by: NFrank Rowand <frank.rowand@am.sony.com>
Signed-off-by: NRob Herring <robh@kernel.org>

drivers/of/platform.c

@@ -76,7 +76,7 @@ EXPORT_SYMBOL(of_find_device_by_node);
  * derive a unique name. If it cannot, then it will prepend names from
  * parent nodes until a unique name can be derived.
  */
-void of_device_make_bus_id(struct device *dev)
+static void of_device_make_bus_id(struct device *dev)
 {
 	struct device_node *node = dev->of_node;
 	const __be32 *reg;

include/linux/of_device.h

@@ -13,7 +13,6 @@ struct device;
 #ifdef CONFIG_OF
 extern const struct of_device_id *of_match_device(
 	const struct of_device_id *matches, const struct device *dev);
-extern void of_device_make_bus_id(struct device *dev);
 
 /**
  * of_driver_match_device - Tell if a driver's of_match_table matches a device.