soc/intel/skylake/acpi: Replace Add(a,b) with ASL 2.0 syntax

Replace `Add (a, b)` with `a + b`.

Change-Id: Id35c24663f529238fe17721b99ad8e93a4f5433f
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60502
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>

src/soc/intel/skylake/acpi/xhci.asl

@@ -17,8 +17,7 @@ Method (UPWE, 3, Serialized)
 	Local0 = Arg1 + ((Arg0 - 1) * 0x10)
 
 	/* Map ((XMEM << 16) + Local0 in PSCR */
-	OperationRegion (PSCR, SystemMemory,
-			 Add (ShiftLeft (Arg2, 16), Local0), 0x10)
+	OperationRegion (PSCR, SystemMemory, ShiftLeft (Arg2, 16) + Local0, 0x10)
 	Field (PSCR, DWordAcc, NoLock, Preserve)
 	{
 		PSCT, 32,
@@ -101,8 +100,7 @@ Device (XHCI)
 		D3HE, 1,	/* D3_hot_en */
 	}
 
-	OperationRegion (XREG, SystemMemory,
-			 Add (ShiftLeft (XMEM, 16), 0x8000), 0x200)
+	OperationRegion (XREG, SystemMemory, ShiftLeft (XMEM, 16) + 0x8000, 0x200)
 	Field (XREG, DWordAcc, Lock, Preserve)
 	{
 		Offset (0x1c4),	/* USB2PMCTRL */