chromeec: Move keyboard backlight code into Chrome EC directory

Since more boards are starting to use the EC provided keyboard
backlight interface move the code to a common place and allow
it to get included in mainboards.

Change-Id: I3f307bbce1a96cdd1c8224b1e89a63d6fedef738
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Reviewed-on: http://review.coreboot.org/11478
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
8 files changed