tree: Replace XOr(a,b,c) with ASL 2.0 syntax

Replace `XOr (a, b, c)` with `c = a ^ b`, respectively `c ^= b` where
possible.

Change-Id: Ic5f67684bbd4ea115c4dae8a4417d88bea0d6b77
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70843
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Elyes Haouas <ehaouas@noos.fr>

src/ec/quanta/it8518/acpi/battery.asl

@@ -106,7 +106,7 @@ Device (BATX)
 		//   ACPI spec     : 0 - mWh   : 1 - mAh
 		//
 		Local7 = SBCM
-		XOr (Local7, One, PBIF[0])
+		PBIF[0] = Local7 ^ One
 
 		//
 		// Information ID 0 -
@@ -282,7 +282,7 @@ Device (BATX)
 			}
 		}
 
-		XOr (DerefOf (PBIF[0]), One, Local6)
+		Local6 = DerefOf (PBIF[0]) ^ One
 
 		If (Local6)
 		{