backlight: Allow properties to be passed at registration

Values such as max_brightness should be set before backlights are
registered, but the current API doesn't allow that. Add a parameter to
backlight_device_register and update drivers to ensure that they
set this correctly.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
diff --git a/drivers/usb/misc/appledisplay.c b/drivers/usb/misc/appledisplay.c
index 4d2952f..3adab04 100644
--- a/drivers/usb/misc/appledisplay.c
+++ b/drivers/usb/misc/appledisplay.c
@@ -202,6 +202,7 @@
 static int appledisplay_probe(struct usb_interface *iface,
 	const struct usb_device_id *id)
 {
+	struct backlight_properties props;
 	struct appledisplay *pdata;
 	struct usb_device *udev = interface_to_usbdev(iface);
 	struct usb_host_interface *iface_desc;
@@ -279,16 +280,16 @@
 	/* Register backlight device */
 	snprintf(bl_name, sizeof(bl_name), "appledisplay%d",
 		atomic_inc_return(&count_displays) - 1);
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.max_brightness = 0xff;
 	pdata->bd = backlight_device_register(bl_name, NULL, pdata,
-						&appledisplay_bl_data);
+					      &appledisplay_bl_data, &props);
 	if (IS_ERR(pdata->bd)) {
 		dev_err(&iface->dev, "Backlight registration failed\n");
 		retval = PTR_ERR(pdata->bd);
 		goto error;
 	}
 
-	pdata->bd->props.max_brightness = 0xff;
-
 	/* Try to get brightness */
 	brightness = appledisplay_bl_get_brightness(pdata->bd);