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/dwc3/core.c b/drivers/usb/dwc3/core.c
index 2e00353..dfd7cf6 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -905,7 +905,7 @@
 	 */
 	hird_threshold = 12;
 
-	dwc->hsphy_mode = usb_get_phy_mode(dev->node);
+	dwc->hsphy_mode = usb_get_phy_mode(dev_ofnode(dev));
 
 	dwc->has_lpm_erratum = dev_read_bool(dev,
 				"snps,has-lpm-erratum");