dm: core: Use dev_has_ofnode() instead of dev_of_valid()

We have two functions which do the same thing. Standardise on
dev_has_ofnode() since there is no such thing as an 'invalid' ofnode in
normal operation: it is either null or missing.

Also move the functions into one place.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/usb/host/usb-uclass.c

@@ -773,7 +773,7 @@ static int usb_child_post_bind(struct udevice *dev)
 	struct usb_dev_plat *plat = dev_get_parent_plat(dev);
 	int val;
 
-	if (!dev_of_valid(dev))
+	if (!dev_has_ofnode(dev))
 		return 0;
 
 	/* We only support matching a few things */