ARM: dts: rockchip: add RK3288 suspend support

ARM: dts: rockchip: add RK3288 suspend support

add pmu sram node for suspend, add global_pwroff pinctrl.
The pmu sram is used to store the resume code.
global_pwroff is held low level at work, it would be pull to high
when entering suspend. reference this in the board DTS file since
some boards need it.

Signed-off-by: Tony Xie <[email protected]>
Signed-off-by: Chris Zhong <[email protected]>
Reviewed-by: Doug Anderson <[email protected]>
Tested-by: Doug Anderson <[email protected]>
Signed-off-by: Heiko Stuebner <[email protected]>