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

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

Change-Id: I523c6b14c127ec7c0eb41078fb2eb92f42d74bd5
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60588
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>

src/soc/intel/apollolake/acpi/northbridge.asl

@@ -95,7 +95,7 @@ Method (_CRS, 0, Serialized)
 
 	/* Read TOLUD */
 	And(\_SB.PCI0.MCHC.TLUD, 0xFFF00000, GMAX)
-	Decrement(GMAX)
+	GMAX--
 	GLEN = GMAX - GMIN + 1
 
 	/* Patch PM02 range based on Memory Size */