ACPI: 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>
UBUNTU: release 3.13.0-1.1endless6
UBUNTU: Start new release

Ignore: yes
Merge pull request #5 from endlessm/shell/3491

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