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/pinctrl/nxp/pinctrl-imx.c b/drivers/pinctrl/nxp/pinctrl-imx.c
index 949d0f3..e130faf 100644
--- a/drivers/pinctrl/nxp/pinctrl-imx.c
+++ b/drivers/pinctrl/nxp/pinctrl-imx.c
@@ -19,7 +19,7 @@
 {
 	struct imx_pinctrl_priv *priv = dev_get_priv(dev);
 	struct imx_pinctrl_soc_info *info = priv->info;
-	int node = config->of_offset;
+	int node = dev_of_offset(config);
 	const struct fdt_property *prop;
 	u32 *pin_data;
 	int npins, size, pin_size;
@@ -176,7 +176,7 @@
 		      struct imx_pinctrl_soc_info *info)
 {
 	struct imx_pinctrl_priv *priv = dev_get_priv(dev);
-	int node = dev->of_offset, ret;
+	int node = dev_of_offset(dev), ret;
 	struct fdtdec_phandle_args arg;
 	fdt_addr_t addr;
 	fdt_size_t size;
@@ -189,7 +189,8 @@
 	priv->dev = dev;
 	priv->info = info;
 
-	addr = fdtdec_get_addr_size(gd->fdt_blob, dev->of_offset, "reg", &size);
+	addr = fdtdec_get_addr_size(gd->fdt_blob, dev_of_offset(dev), "reg",
+				    &size);
 
 	if (addr == FDT_ADDR_T_NONE)
 		return -EINVAL;