nissa: Enable keyboard backlight GPIO setting
nissa: Enable keyboard backlight GPIO setting

Enable setting the keyboard backlight control pin.

BUG=b:227858348
TEST=zmake build nivviks; flash & run
BRANCH=none

Signed-off-by: Andrew McRae <44ad1424cfc8411c96d9181798ca41ae55709dfb@google.com>
Change-Id: Ifad41e94bd8d08b6a1d9af976d62da289e8e7e3b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3563452
Reviewed-by: Peter Marheine <ef0b2c492edde94778d7465bfbaeed52c5be6858@chromium.org>

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