dm: gpio: sandbox: Use dev_read...() functions to access DT

Use the new dev_read...() functions to access the device tree, so that a
live tree can be used.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/gpio/sandbox.c

@@ -198,10 +198,8 @@ static int sandbox_gpio_ofdata_to_platdata(struct udevice *dev)
 {
 	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
 
-	uc_priv->gpio_count = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
-					     "num-gpios", 0);
-	uc_priv->bank_name = fdt_getprop(gd->fdt_blob, dev_of_offset(dev),
-					 "gpio-bank-name", NULL);
+	uc_priv->gpio_count = dev_read_u32_default(dev, "num-gpios", 0);
+	uc_priv->bank_name = dev_read_string(dev, "gpio-bank-name");
 
 	return 0;
 }
@@ -210,10 +208,9 @@ static int gpio_sandbox_probe(struct udevice *dev)
 {
 	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
 
-	if (dev_of_offset(dev) == -1) {
+	if (!dev_of_valid(dev))
 		/* Tell the uclass how many GPIOs we have */
 		uc_priv->gpio_count = CONFIG_SANDBOX_GPIO_COUNT;
-	}
 
 	dev->priv = calloc(sizeof(struct gpio_state), uc_priv->gpio_count);