spi: Tidy up get/set of device node

This code is a bit odd in that it only reads and updates the livetree
version of the device ofnode. This means it won't work with flattree.
Update the code to work as it was presumably intended.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 1b91517..54d03d0 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -332,15 +332,14 @@
 };
 
 #if IS_ENABLED(CONFIG_DM)
-static inline void mtd_set_of_node(struct mtd_info *mtd,
-				   const struct device_node *np)
+static inline void mtd_set_ofnode(struct mtd_info *mtd, ofnode node)
 {
-	mtd->dev->node.np = np;
+	mtd->dev->node = node;
 }
 
-static inline const struct device_node *mtd_get_of_node(struct mtd_info *mtd)
+static inline const ofnode mtd_get_ofnode(struct mtd_info *mtd)
 {
-	return mtd->dev->node.np;
+	return mtd->dev->node;
 }
 #else
 struct device_node;