ARM: dts: rockchip: add suspend settings for rk3288-evb-rk808

Add suspend-voltages and necessary pin-states for suspend on
rk3288-evb-rk808 boards. global_pwroff would be pulled high when
RK3288 entering suspend, this pin is a sleep signal for RK808, so
RK808 could goto sleep mode, and some regulators would be disable.

Signed-off-by: Chris Zhong <zyw@rock-chips.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Tested-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>