acpi-video-detect: Remove old API

Remove the old backlight interface selection API now that all drivers
have been ported to the new 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>