UPSTREAM: ec/lenovo/h8: Use older syntax for bit shift

Currently, when using `iasl` 20140926-32 [Oct  1 2014] from Debian 8
(Jessie/stable), the build of the Lenovo X60 fails due to syntax errors.

ASL 2.0 supports `<<`. For consistency, right now, coreboot still uses
the old syntax. So use `ShiftLeft` instead, which also fixes the build
issue with older ASL compilers.

BUG=none
BRANCH=none
TEST=none

Change-Id: I030413bf10db3d8b2435d1fd55e96c7a9a0c457d
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: db94213640
Original-Change-Id: Id7e309c31612387da3920cf7d846b358ac2bdc71
Original-Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Original-Reviewed-on: https://review.coreboot.org/18520
Original-Tested-by: build bot (Jenkins)
Original-Reviewed-by: Philippe Mathieu-Daud <f4bug@amsat.org>
Original-Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://chromium-review.googlesource.com/450377

src/ec/lenovo/h8/acpi/ec.asl

@@ -363,7 +363,7 @@ Device(EC)
 		/* Report tablet mode switch state */
 		Method (MHKG, 0, NotSerialized)
 		{
-			Return (TBSW << 3)
+			Return (ShiftLeft(TBSW, 3))
 		}
 		/* Mute audio */
 		Method (SSMS, 1, NotSerialized)