mb/samsung/stumpy: Drop ACPI brightness controls

Stumpy is a Chromebox without a built-in display, and now
that default_brightness_levels.asl is no longer required
for all boards in a platform, drop it and the default panel
definition.

Test: build/boot stumpy

Change-Id: Iaf475f3529dd19330ea46532e9ffd20b44893f7e
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40046
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/mainboard/samsung/stumpy/devicetree.cb

@@ -1,6 +1,4 @@
 chip northbridge/intel/sandybridge
-	# IGD Displays
-	register "gfx" = "GMA_STATIC_DISPLAYS(0)"
 
 	# Enable DisplayPort 1 Hotplug with 6ms pulse
 	register "gpu_dp_d_hotplug" = "0x06"

src/mainboard/samsung/stumpy/dsdt.asl

@@ -28,8 +28,6 @@ DefinitionBlock(
 		{
 			#include <northbridge/intel/sandybridge/acpi/sandybridge.asl>
 			#include <southbridge/intel/bd82x6x/acpi/pch.asl>
-
-			#include <drivers/intel/gma/acpi/default_brightness_levels.asl>
 		}
 	}