mb/google/brox: Add default ACPI brightness levels

Kernel need the default brightness steps. Otherwise following error
messages are observed in the kernel:
[Firmware Bug]: ACPI(GFX0) defines _DOD but not _DOS
ACPI BIOS Error (bug): Could not resolve symbol [^^XBCL], AE_NOT_FOUND
ACPI Error: Aborting method \_SB.PCI0.GFX0.LCD0._BCL due to previous
error (AE_NOT_FOUND)

BUG=b:346807006
TEST=Build Brox BIOS image and boot to OS. Ensure that the concerned
error messages are resolved. Ensure that the backlight controls are
functional.

Change-Id: Icd569b0efef31908edb1b7dc384e60a16fc5bd0c
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83152
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Shelley Chen <shchen@google.com>
Reviewed-by: Matt DeVillier <matt.devillier@amd.corp-partner.google.com>
diff --git a/src/mainboard/google/brox/dsdt.asl b/src/mainboard/google/brox/dsdt.asl
index 6ae4694..30e9fe1 100644
--- a/src/mainboard/google/brox/dsdt.asl
+++ b/src/mainboard/google/brox/dsdt.asl
@@ -26,6 +26,7 @@
 			#include <soc/intel/common/block/acpi/acpi/northbridge.asl>
 			#include <soc/intel/alderlake/acpi/southbridge.asl>
 			#include <soc/intel/alderlake/acpi/tcss.asl>
+			#include <drivers/intel/gma/acpi/default_brightness_levels.asl>
 		}
 	}