drivers/intel/gma/acpi: Replace Subtract(a,b) with ASL 2.0 syntax

Replace `Subtract (a, b)` with `a - b`.

Change-Id: I4f6ffd6bbf6a37e041879e50fe41ce3cc856371f
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60497
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
diff --git a/src/drivers/intel/gma/acpi/common.asl b/src/drivers/intel/gma/acpi/common.asl
index 254a66d..02169ae 100644
--- a/src/drivers/intel/gma/acpi/common.asl
+++ b/src/drivers/intel/gma/acpi/common.asl
@@ -9,7 +9,7 @@
 		Store (Match (BRIG, MEQ, Arg0, MTR, Zero, 2), Local0)
 		If (LEqual (Local0, Ones))
 		{
-			Return (Subtract(SizeOf(BRIG), One))
+			Return (SizeOf(BRIG) - 1)
 		}
 		Return (Local0)
 	}
@@ -56,7 +56,7 @@
 			Notify (LCD0, 0x86)
 		} Else {
 			Store (BRID (XBQC ()), Local0)
-			If (LNotEqual (Local0, Subtract(SizeOf(BRIG), One)))
+			If (LNotEqual (Local0, SizeOf(BRIG) - 1))
 			{
 				Increment (Local0)
 			}