sandbox: phy: Update driver for livetree

Update the sandbox phy driver to support livetree.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/phy/sandbox-phy.c b/drivers/phy/sandbox-phy.c
index 9ad820c..867c6fe 100644
--- a/drivers/phy/sandbox-phy.c
+++ b/drivers/phy/sandbox-phy.c
@@ -80,8 +80,7 @@
 
 	priv->initialized = false;
 	priv->on = false;
-	priv->broken = fdtdec_get_bool(gd->fdt_blob, dev_of_offset(dev),
-				       "broken");
+	priv->broken = dev_read_bool(dev, "broken");
 
 	return 0;
 }