Use the hardware device in struct fb_info.device as parent of the
backlight device. Aligns the driver with the rest of the codebase
and prepares fbdev for making struct fb_info.dev optional.
v2:
	* add Cc: tag (Dan)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230613110953.24176-23-tzimmermann@suse.de
 
        memset(&props, 0, sizeof(struct backlight_properties));
        props.type = BACKLIGHT_RAW;
        props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
-       bd = backlight_device_register(name, rinfo->info->dev, pdata,
+       bd = backlight_device_register(name, rinfo->info->device, pdata,
                                       &radeon_bl_data, &props);
        if (IS_ERR(bd)) {
                rinfo->info->bl_dev = NULL;