apple-gmux: Port to new backlight interface selection API

Port the backlight selection logic to the new backlight interface
selection API.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/platform/x86/apple-gmux.c

@@ -550,8 +550,7 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
 	 * backlight control and supports more levels than other options.
 	 * Disable the other backlight choices.
 	 */
-	acpi_video_dmi_promote_vendor();
-	acpi_video_unregister_backlight();
+	acpi_video_set_dmi_backlight_type(acpi_backlight_vendor);
 	apple_bl_unregister();
 
 	gmux_data->power_state = VGA_SWITCHEROO_ON;