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/usb/musb-new/pic32.c b/drivers/usb/musb-new/pic32.c
index c888c64..ed6da19 100644
--- a/drivers/usb/musb-new/pic32.c
+++ b/drivers/usb/musb-new/pic32.c
@@ -219,7 +219,7 @@
 	struct musb_host_data *mdata = &pdata->mdata;
 	struct fdt_resource mc, glue;
 	void *fdt = (void *)gd->fdt_blob;
-	int node = dev->of_offset;
+	int node = dev_of_offset(dev);
 	void __iomem *mregs;
 	int ret;
 
diff --git a/drivers/usb/musb-new/ti-musb.c b/drivers/usb/musb-new/ti-musb.c
index 1c15aa2..852f07f 100644
--- a/drivers/usb/musb-new/ti-musb.c
+++ b/drivers/usb/musb-new/ti-musb.c
@@ -83,7 +83,7 @@
 {
 	struct ti_musb_platdata *platdata = dev_get_platdata(dev);
 	const void *fdt = gd->fdt_blob;
-	int node = dev->of_offset;
+	int node = dev_of_offset(dev);
 	int phys;
 	int ctrl_mod;
 	int usb_index;
@@ -178,7 +178,7 @@
 {
 	struct ti_musb_platdata *platdata = dev_get_platdata(dev);
 	const void *fdt = gd->fdt_blob;
-	int node = dev->of_offset;
+	int node = dev_of_offset(dev);
 	int ret;
 
 	ret = ti_musb_ofdata_to_platdata(dev);
@@ -209,7 +209,7 @@
 	int node;
 	int ret;
 
-	for (node = fdt_first_subnode(fdt, parent->of_offset); node > 0;
+	for (node = fdt_first_subnode(fdt, dev_of_offset(parent)); node > 0;
 	     node = fdt_next_subnode(fdt, node)) {
 		struct udevice *dev;
 		const char *name = fdt_get_name(fdt, node, NULL);