tree/acpi: Replace constant "Zero" with actual number

Change-Id: I5a3e3506415f424bf0fdd48fc449520a76622af5
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/71525
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Elyes Haouas <ehaouas@noos.fr>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/amd/cezanne/acpi/pci0.asl

@@ -6,7 +6,7 @@ Device(PCI0) {
 	External(TOM1, IntObj)		/* Generated by root_complex.c */
 
 	Method(_BBN, 0, NotSerialized) {
-		Return(Zero) /* Bus number = 0 */
+		Return(0) /* Bus number = 0 */
 	}
 
 	Method(_STA, 0, NotSerialized) {