mb: Set coreboot as DSDT's manufacturer model ID

Field 'OEMID' & "OEM Table ID" are related to DSDT table
not to mainboard.
So use macro to set them respectvely to "COREv4" and
"COREBOOT".

Change-Id: I060e07a730e721df4a86128ee89bfe168c69f31e
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/29790
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: David Guckian

src/mainboard/amd/bettong/acpi/routing.asl

@@ -15,7 +15,8 @@
  */
 
 /*
-DefinitionBlock ("DSDT.AML","DSDT",0x01,"XXXXXX","XXXXXXXX",0x00010001
+#include <arch/acpi.h>
+DefinitionBlock ("DSDT.AML", "DSDT", 0x01, OEM_ID, ACPI_TABLE_CREATOR, 0x00010001
 		)
 	{
 		#include "routing.asl"