CHROMIUM: dts: spring: Enable cros_ec-charger in device tree.

CHROMIUM: dts: spring: Enable cros_ec-charger in device tree.

Signed-off-by: Todd Broch <tbroch@chromium.org>
BUG=chrome-os-partner:17927
TEST=manual,
1. boot kernel, login as root
2. plug in various PSU's
3. check online status
   power-supply-info | grep online
   online:           yes
4. unplug PSU
   power-supply-info | grep online
   online:           no

Change-Id: Idc1d9fb52f9288ca6b0cce243be18087a51a1803
Reviewed-on: https://gerrit.chromium.org/gerrit/44683
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Commit-Queue: Todd Broch <tbroch@chromium.org>
Tested-by: Todd Broch <tbroch@chromium.org>