google/gru: correct backlight gpio

it uses backlight enable pin as backlight gpio currently,
correct it and define the right backlight gpio.

Change-Id: I7c5abfd5bbbae015b899f3edc8892ea32bf82463
Signed-off-by: Lin Huang <hl@rock-chips.com>
Reviewed-on: https://review.coreboot.org/22529
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
3 files changed