sandbox: usb: Convert emulators to livetree

Update the sandbox flash and hub USB emulators to support a live device
tree.

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

drivers/usb/emul/sandbox_flash.c

@@ -371,10 +371,8 @@ err:
 static int sandbox_flash_ofdata_to_platdata(struct udevice *dev)
 {
 	struct sandbox_flash_plat *plat = dev_get_platdata(dev);
-	const void *blob = gd->fdt_blob;
 
-	plat->pathname = fdt_getprop(blob, dev_of_offset(dev),
-				     "sandbox,filepath", NULL);
+	plat->pathname = dev_read_string(dev, "sandbox,filepath");
 
 	return 0;
 }

drivers/usb/emul/sandbox_hub.c

@@ -277,8 +277,7 @@ static int sandbox_child_post_bind(struct udevice *dev)
 {
 	struct sandbox_hub_platdata *plat = dev_get_parent_platdata(dev);
 
-	plat->port = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev), "reg",
-				    -1);
+	plat->port = dev_read_u32_default(dev, "reg", -1);
 
 	return 0;
 }