dm: core: Access device ofnode through functions

At present ofnode is present in the device even if it is never used. With
of-platdata this field is not used, so can be removed. In preparation for
this, change the access to go through inline functions.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/usb/musb-new/ti-musb.c b/drivers/usb/musb-new/ti-musb.c
index 81b12fa..75cf181 100644
--- a/drivers/usb/musb-new/ti-musb.c
+++ b/drivers/usb/musb-new/ti-musb.c
@@ -289,7 +289,7 @@
 	ofnode node;
 	int ret;
 
-	ofnode_for_each_subnode(node, parent->node) {
+	ofnode_for_each_subnode(node, dev_ofnode(parent)) {
 		struct udevice *dev;
 		const char *name = ofnode_get_name(node);
 		enum usb_dr_mode dr_mode;