mb/google/kahlee/acpi: Replace Add(a,b,c) with ASL 2.0 syntax

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

Change-Id: If80d97abc831e17bc8bc6e379bbae26e65db23f1
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60491
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>

src/mainboard/google/kahlee/variants/baseboard/include/baseboard/acpi/thermal.asl

@@ -24,7 +24,7 @@ Scope (\_TZ)
 			Multiply (Arg0, 10, Local0)
 
 			/* Convert to Kelvin */
-			Add (Local0, 2732, Local0)
+			Local0 += 2732
 
 			Return (Local0)
 		}