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>
diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index a7f6412..0dec3f5 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -550,8 +550,7 @@
 	 * 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;