nb/intel/gm45: Use ASL 2.0 syntax

Tested with BUILD_TIMELESS=1, Roda RK9 does not change.

Change-Id: Ibb9b627de85eb09bdc977af55880366e4e49f3ac
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43173
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>

src/northbridge/intel/gm45/acpi/hostbridge.asl

@@ -208,8 +208,8 @@ Method (_CRS, 0, Serialized)
 	 * Enter actual TOLUD. The TOLUD register contains bits 20-31 of
 	 * the top of memory address.
 	 */
-	ShiftLeft (^MCHC.TLUD, 20, PMIN)
-	Add(Subtract(PMAX, PMIN), 1, PLEN)
+	PMIN = ^MCHC.TLUD << 20
+	PLEN = PMAX - PMIN + 1
 
 	Return (MCRS)
 }