arm64: dts: rockchip: Designate the system power controller on QuartzPro64

Designate the primary RK806 PMIC on the Pine64 QuartzPro64 as the system
power controller, so the board shuts down properly on poweroff(8).

Fixes: 152d3d070a9c ("arm64: dts: rockchip: Add QuartzPro64 SBC device tree")
Signed-off-by: Dragan Simic <dsimic@manjaro.org>
Link: https://lore.kernel.org/r/c602dfb3972a0844f2a87b6245bdc5c3378c5989.1712512497.git.dsimic@manjaro.org
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Author: Dragan Simic

arch/arm64/boot/dts/rockchip/rk3588-quartzpro64.dts

@@ -456,6 +456,7 @@
 			    <&rk806_dvs2_null>, <&rk806_dvs3_null>;
 		pinctrl-names = "default";
 		spi-max-frequency = <1000000>;
+		system-power-controller;
 
 		vcc1-supply = <&vcc4v0_sys>;
 		vcc2-supply = <&vcc4v0_sys>;