dm: core: make simple-bus compatible to simple-mfd

Simple MFD devices can bind children without special bus configuration.
Like Linux, let's handle "simple-mfd" in the same way as "simple-bus".

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Simon Glass <sjg@chromium.org>

drivers/core/simple-bus.c

@@ -53,6 +53,7 @@ UCLASS_DRIVER(simple_bus) = {
 
 static const struct udevice_id generic_simple_bus_ids[] = {
 	{ .compatible = "simple-bus" },
+	{ .compatible = "simple-mfd" },
 	{ }
 };