mb/google/drallion: Add VBT, ACPI brightness controls

Enables display backlight control under Windows.
VBT extracted from stock ChromeOS firmware Google_Drallion.12930.543.0.

TEST=build/boot Win11 on drallion, verify OS backlight control
available and functional.

Change-Id: I85065f22b825a7616fa4ac632c42ae7972091e24
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/72579
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/mainboard/google/drallion/Kconfig

@@ -13,6 +13,7 @@ config BOARD_GOOGLE_BASEBOARD_DRALLION
 	select HAVE_ACPI_TABLES
 	select HAVE_SPD_IN_CBFS
 	select I2C_TPM
+	select INTEL_GMA_HAVE_VBT
 	select INTEL_LPSS_UART_FOR_CONSOLE
 	select MAINBOARD_HAS_CHROMEOS
 	select MAINBOARD_HAS_TPM2

src/mainboard/google/drallion/dsdt.asl

@@ -22,6 +22,7 @@ DefinitionBlock(
 		{
 			#include <soc/intel/common/block/acpi/acpi/northbridge.asl>
 			#include <soc/intel/cannonlake/acpi/southbridge.asl>
+			#include <drivers/intel/gma/acpi/default_brightness_levels.asl>
 		}
 		/* Per board variant mainboard hooks. */
 		#include <variant/acpi/mainboard.asl>

src/mainboard/google/drallion/variants/drallion/devicetree.cb

@@ -220,6 +220,7 @@ chip soc/intel/cannonlake
 	device domain 0 on
 		device pci 00.0 on  end # Host Bridge
 		device pci 02.0 on
+			register "gfx" = "GMA_DEFAULT_PANEL(0)"
 			chip drivers/gfx/generic
 				register "device_count" = "1"
 				register "device[0].name" = ""LCD""