mb/gigabyte/ga-h61m-series: Drop useless `mainboard.asl`

Was copy-pasted from another board and is completely useless.

Change-Id: Iedb03284b4509597cff5d39dda4f98669f2e814b
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50502
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/mainboard/gigabyte/ga-h61m-series/acpi/mainboard.asl

@@ -1,9 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-
-Scope (\_SB)
-{
-	Device (PWRB)
-	{
-		Name (_HID, EisaId("PNP0C0C"))
-	}
-}

src/mainboard/gigabyte/ga-h61m-series/dsdt.asl

@@ -12,7 +12,6 @@ DefinitionBlock(
 )
 {
 	#include <acpi/dsdt_top.asl>
-	#include "acpi/mainboard.asl"
 	#include "acpi/platform.asl"
 	#include <cpu/intel/common/acpi/cpu.asl>
 	#include <southbridge/intel/common/acpi/platform.asl>