dm: core: Allow uclass to set up a device's child before it is probed

Some buses need to set up their devices before they can be used. This setup
may well be common to all buses in a particular uclass. Support a common
pre-probe method for the uclass, called before any bus devices are probed.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

include/dm/uclass.h

@@ -83,6 +83,7 @@ struct uclass_driver {
 	int (*post_probe)(struct udevice *dev);
 	int (*pre_remove)(struct udevice *dev);
 	int (*child_post_bind)(struct udevice *dev);
+	int (*child_pre_probe)(struct udevice *dev);
 	int (*init)(struct uclass *class);
 	int (*destroy)(struct uclass *class);
 	int priv_auto_alloc_size;