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/net/mdio-ipq4019.c b/drivers/net/mdio-ipq4019.c
index 13a8856..50134b4 100644
--- a/drivers/net/mdio-ipq4019.c
+++ b/drivers/net/mdio-ipq4019.c
@@ -107,8 +107,8 @@
 
 static int ipq4019_mdio_bind(struct udevice *dev)
 {
-	if (ofnode_valid(dev->node))
-		device_set_name(dev, ofnode_get_name(dev->node));
+	if (ofnode_valid(dev_ofnode(dev)))
+		device_set_name(dev, ofnode_get_name(dev_ofnode(dev)));
 
 	return 0;
 }