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/mtd/nand/raw/octeontx_nand.c b/drivers/mtd/nand/raw/octeontx_nand.c
index 96a5fe6..64433cf 100644
--- a/drivers/mtd/nand/raw/octeontx_nand.c
+++ b/drivers/mtd/nand/raw/octeontx_nand.c
@@ -1999,7 +1999,7 @@
 static int octeontx_nfc_chips_init(struct octeontx_nfc *tn)
 {
 	struct udevice *dev = tn->dev;
-	ofnode node = dev->node;
+	ofnode node = dev_ofnode(dev);
 	ofnode nand_node;
 	int nr_chips = of_get_child_count(node);
 	int ret;