drawcia: Add keyboard backlight support
drawcia: Add keyboard backlight support

BUG=none
BRANCH=none
TEST=Set FW_CONFIG to 0x0100 and make sure "ectool inventory"
had keyboard backlight present.

Signed-off-by: Devin Lu <052fe648504800b810f29702ef4f3db83fad68bf@quantatw.com>
Change-Id: I7e0fd3ee42d5829dd6c81427c6ecbb359a5c385c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2331977
Reviewed-by: Diana Z <cb2016afc7183e5356c690dc63b4ba817470501a@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec