arm64: dts: rockchip: add ap_pwroff and ddrio_pwroff pins for rk3399

There are two sleep related pins on rk3399: ap_pwroff and ddrio_pwroff.
Let's add the definition of these two pins to rk3399's main dtsi file so
that boards can use them.

These two pins are similar to the global_pwroff and ddrio_pwroff pins in
rk3288 and are expected to be used in the same way: boards will likely
want to configure these pinctrl settings in their global pinctrl hog
list.

Note that on rk3288 there were two additional pins in the "sleep"
section: "ddr0_retention" and "ddr1_retention".  On rk3288 designs these
pins appeared to actually route from rk3288 back to rk3288.  Presumably
on rk3399 this is simply not needed since the pins don't appear to exist
there.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3399.dtsi

@@ -1045,6 +1045,16 @@ i2s1_2ch_bus: i2s1-2ch-bus {
 			};
 		};
 
+		sleep {
+			ap_pwroff: ap-pwroff {
+				rockchip,pins = <1 5 RK_FUNC_1 &pcfg_pull_none>;
+			};
+
+			ddrio_pwroff: ddrio-pwroff {
+				rockchip,pins = <0 1 RK_FUNC_1 &pcfg_pull_none>;
+			};
+		};
+
 		spdif {
 			spdif_bus: spdif-bus {
 				rockchip,pins =