remove display_backlight since chromebox won't use it

BUG=chrome-os-partner:37338
BRANCH=R42/TOT
TEST=The brightness up/down key work

Change-Id: I5a4bea3efc469b282bef019beb6b27c495637ea4
Signed-off-by: Zhuo-hao Lee <zhuo-hao.lee@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/255367
Reviewed-by: Bernie Thompson <bhthompson@chromium.org>
(cherry picked from commit 46d78fc8f472214dba86c4985f0b792193566819)
Reviewed-on: https://chromium-review.googlesource.com/256230
Reviewed-by: Shawn N <shawnn@chromium.org>
diff --git a/baseboard-jecht/make.conf b/baseboard-jecht/make.conf
index bc66cfe..1142d93 100644
--- a/baseboard-jecht/make.conf
+++ b/baseboard-jecht/make.conf
@@ -2,9 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-USE="${USE} jecht"
-USE="${USE} lockvt"
-USE="${USE} legacy_power_button legacy_keyboard wireless38"
+USE="${USE} -display_backlight jecht legacy_keyboard legacy_power_button"
+USE="${USE} lockvt wireless38"
 
 # WiFi and BT driver firmware
 LINUX_FIRMWARE="marvell-pcie8897 iwlwifi-7260 ibt-hw"