In the pattern of many other devices, support a system-sleep pin
configuration.
Signed-off-by: NBrian Norris <briannorris@chromium.org>
Reviewed-by: NDouglas Anderson <dianders@chromium.org>
Tested-by: NCaesar Wang <wxt@rock-chips.com>
Signed-off-by: NMark Brown <broonie@kernel.org>