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/spi/fsl_dspi.c b/drivers/spi/fsl_dspi.c
index b8c0216..c17a552 100644
--- a/drivers/spi/fsl_dspi.c
+++ b/drivers/spi/fsl_dspi.c
@@ -460,8 +460,10 @@
 		return -EINVAL;
 	}
 
-	ofnode_read_u32(dev->node, "fsl,spi-cs-sck-delay", &cs_sck_delay);
-	ofnode_read_u32(dev->node, "fsl,spi-sck-cs-delay", &sck_cs_delay);
+	ofnode_read_u32(dev_ofnode(dev), "fsl,spi-cs-sck-delay",
+			&cs_sck_delay);
+	ofnode_read_u32(dev_ofnode(dev), "fsl,spi-sck-cs-delay",
+			&sck_cs_delay);
 
 	/* Set PCS to SCK delay scale values */
 	ns_delay_scale(&pcssck, &cssck, cs_sck_delay, priv->bus_clk);