This enables adding the backlight driver to boards that may or may not
come with a keyboard backlight function.
It's the responsibility of the EC to report if that feature exists, but
that's not a big extra burden given that it already keeps track of
everything else related to the backlight.
BUG=b:64705535
BRANCH=none
CQ-DEPEND=CL:620595
TEST=configured KBLE manually and noticed the presence/absence of
/sys/devices/platform/GOOG0002:00/ on a Chrome OS Linux kernel,
corresponding to the value reported by the EC.
Change-Id: Idc36bfaa6e69581ba19b52d37af6956f63cfdb8f
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/21099
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
4bd68b8e4f