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/mtu3/mtu3_plat.c b/drivers/usb/mtu3/mtu3_plat.c
index c951107..b097471 100644
--- a/drivers/usb/mtu3/mtu3_plat.c
+++ b/drivers/usb/mtu3/mtu3_plat.c
@@ -173,7 +173,7 @@
 		return -ENODEV;
 	}
 
-	ssusb->dr_mode = usb_get_dr_mode(child->node);
+	ssusb->dr_mode = usb_get_dr_mode(dev_ofnode(child));
 
 	if (ssusb->dr_mode == USB_DR_MODE_UNKNOWN ||
 		ssusb->dr_mode == USB_DR_MODE_OTG)
@@ -313,7 +313,7 @@
 	ofnode node;
 	int ret;
 
-	node = ofnode_by_compatible(parent->node, "mediatek,ssusb");
+	node = ofnode_by_compatible(dev_ofnode(parent), "mediatek,ssusb");
 	if (!ofnode_valid(node))
 		return -ENODEV;