dm: core: allow device_bind() to not return a device pointer

This is useful when we want to bind a device, but do not need the
pointer to the device.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/include/dm/lists.h b/include/dm/lists.h
index 61610e6..4513d6a 100644
--- a/include/dm/lists.h
+++ b/include/dm/lists.h
@@ -68,7 +68,7 @@
  * @parent:	Parent device
  * @drv_name:	Name of driver to attach to this parent
  * @dev_name:	Name of the new device thus created
- * @devp:	Returns the newly bound device
+ * @devp:	If non-NULL, returns the newly bound device
  */
 int device_bind_driver(struct udevice *parent, const char *drv_name,
 		       const char *dev_name, struct udevice **devp);
@@ -83,7 +83,7 @@
  * @drv_name:	Name of driver to attach to this parent
  * @dev_name:	Name of the new device thus created
  * @node:	Device tree node
- * @devp:	Returns the newly bound device
+ * @devp:	If non-NULL, returns the newly bound device
  */
 int device_bind_driver_to_node(struct udevice *parent, const char *drv_name,
 			       const char *dev_name, int node,