soc/intel/acpi: Replace Decrement(a) with ASL 2.0 syntax

Replace `Decrement (a)` with `a--`.

Change-Id: I5c9290aaa9fc969368d5934e4f48a75d915ca5ff
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70592
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
diff --git a/src/soc/intel/baytrail/acpi/dptf/charger.asl b/src/soc/intel/baytrail/acpi/dptf/charger.asl
index b8c6d14..4169b94 100644
--- a/src/soc/intel/baytrail/acpi/dptf/charger.asl
+++ b/src/soc/intel/baytrail/acpi/dptf/charger.asl
@@ -27,7 +27,7 @@
 	{
 		/* Convert size of PPSS table to index */
 		Store (SizeOf (\_SB.CHPS), Local0)
-		Decrement (Local0)
+		Local0--
 
 		/* Check if charging is disabled (AC removed) */
 		If (LEqual (\PWRS, Zero)) {