support Thinkpad X1 Carbon 2nd generation's adaptive keyboard

support Thinkpad X1 Carbon 2nd generation's adaptive keyboard

Submit patch V4 to support Adaptive Keyboard on Thinkpad X1 Carbon 2nd
generation according to Tobias's comments.

Thanks,
Shuduo

>From b153a7b14791c6e01892c0e274e23eefd625fb8d Mon Sep 17 00:00:00 2001
From: Shuduo Sang <shuduo.sang@canonical.com>
Date: Mon, 3 Mar 2014 14:29:32 +0800
Subject: [PATCH] support thinkpad X1 Carbon's adaptive keyboard

Thinkpad X1 Carbon's adaptive keyboard has five modes including Home
mode, Web browser mode, Web conference mode, Function mode and Lay-flat
mode. We support Home mode and Function mode currently.

Signed-off-by: Bruce Ma <bruce.ma@canonical.com>
Signed-off-by: Shuduo Sang <shuduo.sang@canonical.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>