mb/lenovo/t430: Add support for ThinkLight

With this patch, the ThinkLight on the ThinkPad T430 can be controlled
through the OS.  The same change was done for the ThinkPad X200 in
b45912f4: mb/lenovo/x200: Add support for ThinkLight

After applying this patch, the light can be controlled like this:

    echo on >/proc/acpi/ibm/light
    echo off >/proc/acpi/ibm/light

Or through sysfs at /sys/class/leds/tpacpi::thinklight

Unfortunately I do not own a T430 to test this.

Change-Id: I1fb1a9d3a84ce12ab9e3f22a699afbfd7cd1688f
Signed-off-by: Stefan Ott <stefan@ott.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40716
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Alexander Couzens <lynxis@fe80.eu>

src/mainboard/lenovo/t430/dsdt.asl

@@ -30,4 +30,5 @@ DefinitionBlock(
 			#include <southbridge/intel/bd82x6x/acpi/pch.asl>
 		}
 	}
+	#include <ec/lenovo/h8/acpi/thinklight.asl>
 }