ACPI: video: Add DMI quirk for GIGABYTE GB-BXBT-2807

The GIGABYTE GB-BXBT-2807 is a mini-PC which uses off the shelf
components, like an Intel GPU which is meant for mobile systems.
As such, it, by default, has a backlight controller exposed.

Unfortunately, the backlight controller only confuses userspace, which
sees the existence of a backlight device node and has the unrealistic
belief that there is actually a backlight there!

Add a DMI quirk to force the backlight off on this system.

Signed-off-by: Jasper St. Pierre <jstpierre@mecheye.net>
Reviewed-by: Chris Chiu <chiu@endlessos.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>