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

Replace `ShiftRight (a, b, c)` with `c = a >> b`. One case was
simplified to just `a >> b`.

Change-Id: I889012b0a3067138e6f02d3fe8e97151effb5c2a
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70840
Reviewed-by: Caveh Jalali <caveh@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>

src/ec/google/chromeec/acpi/battery.asl

@@ -209,7 +209,7 @@ Method (BBST, 4, Serialized)
 		Local2 = BTDF
 
 		// See if within ~6% of full
-		ShiftRight (Local2, 4, Local3)
+		Local3 = Local2 >> 4
 		If (Local1 > Local2 - Local3 && Local1 < Local2 + Local3)
 		{
 			Local1 = Local2