Add 'kblight' EC capability

Currently only Link EC controls keyboard backlight. Adding a 'kblight'
capability so individual test can query this.

BUG=chrome-os-partner:20823
TEST=Pass firmware_ECLidSwitch on Spring

Change-Id: I27b9ca5e5e18e964586bd9a02d7835a4db6f1dd0
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/61531
Reviewed-by: Tom Wai-Hong Tam <waihong@chromium.org>
2 files changed