gma ACPI: Make brightness levels a per board setting

Those are actually board specific. Keep the old value as defaults,
though. The defaults are included by all affected boards.

Change-Id: Ib865c7b4274f2ea3181a89fc52701b740f9bab7d
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: http://review.coreboot.org/11705
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Vladimir Serbinenko <phcoder@gmail.com>

util/autoport/sandybridge.go

@@ -135,6 +135,8 @@ func (i sandybridgemc) Scan(ctx Context, addr PCIDevData) {
 
 	DSDTPCI0Includes = append(DSDTPCI0Includes, DSDTInclude{
 		File: "northbridge/intel/sandybridge/acpi/sandybridge.asl",
+	}, DSDTInclude{
+		File: "drivers/intel/gma/acpi/default_brightness_levels.asl",
 	})
 }