dm: core: Add a required struct declaration

This file uses struct driver, so declare it at the top in case the
header-inclusion order is not as expected.
Signed-off-by: NSimon Glass <sjg@chromium.org>

include/dm/device-internal.h

@@ -15,6 +15,7 @@
 #include <dm/ofnode.h>
 
 struct device_node;
+struct driver_info;
 struct udevice;
 
 /*