mb/asus/p8z77-m_pro: Remove PS/2 keyboard & mouse duplicate

PS/2 keyboard and mouse devices are declared twice in the DSDT, once
in mainboard and once in southbridge. It would appear in Windows
Device Manager as two PS/2 keyboards and two PS/2 mouses, all with
resource conflicts. This change drops the declaration from mainboard.

The issue was discovered when this setup was copied for p8z77-m and
being boot tested.

Change-Id: I746a960aaf3992acbcb6a7364641fc4fd12002d2
Signed-off-by: Keith Hui <buurin@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41225
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/asus/p8z77-m_pro/dsdt.asl

@@ -11,7 +11,6 @@ DefinitionBlock(
 )
 {
 	#include "acpi/platform.asl"
-	#include "acpi/superio.asl"
 	#include <cpu/intel/common/acpi/cpu.asl>
 	#include <southbridge/intel/common/acpi/platform.asl>