soc/intel/cannonlake: Add platform.asl

Include common platform.asl to have generic indication of power
transition state of system.

TEST=Enter and resume from S3, check the post code had been changed to
0096 and 0097.

Change-Id: Ic38ac6d7e60441caeba5c088c9dbe4d901355782
Signed-off-by: Lijian Zhao <lijian.zhao@intel.com>
Reviewed-on: https://review.coreboot.org/22111
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Pratikkumar V Prajapati <pratikkumar.v.prajapati@intel.com>

src/mainboard/intel/cannonlake_rvp/dsdt.asl

@@ -24,6 +24,9 @@ DefinitionBlock(
 	0x20110725	// OEM revision
 )
 {
+	// Some generic macros
+	#include <soc/intel/cannonlake/acpi/platform.asl>
+
 	// global NVS and variables
 	#include <soc/intel/cannonlake/acpi/globalnvs.asl>