dm: core: Replace of_offset with accessor

At present devices use a simple integer offset to record the device tree
node associated with the device. In preparation for supporting a live
device tree, which uses a node pointer instead, refactor existing code to
access this field through an inline function.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/remoteproc/rproc-uclass.c b/drivers/remoteproc/rproc-uclass.c
index 200cf61..b6e67f2 100644
--- a/drivers/remoteproc/rproc-uclass.c
+++ b/drivers/remoteproc/rproc-uclass.c
@@ -116,7 +116,7 @@
 
 	if (!dev->platdata) {
 #if CONFIG_IS_ENABLED(OF_CONTROL)
-		int node = dev->of_offset;
+		int node = dev_of_offset(dev);
 		const void *blob = gd->fdt_blob;
 		bool tmp;
 		if (!blob) {
diff --git a/drivers/remoteproc/ti_power_proc.c b/drivers/remoteproc/ti_power_proc.c
index 76ac3be..bb7a145 100644
--- a/drivers/remoteproc/ti_power_proc.c
+++ b/drivers/remoteproc/ti_power_proc.c
@@ -33,7 +33,7 @@
 static int ti_of_to_priv(struct udevice *dev,
 			 struct ti_powerproc_privdata *priv)
 {
-	int node = dev->of_offset;
+	int node = dev_of_offset(dev);
 	const void *blob = gd->fdt_blob;
 	int tmp;