ARM: rockchip: add power-management-unit

The pmu is needed to bring up the cores during smp operations and later
also other system parts. Therefore add a node and documentation for it.
Signed-off-by: NHeiko Stuebner <heiko@sntech.de>
Tested-by: NUlrich Prinz <ulrich.prinz@googlemail.com>

Documentation/devicetree/bindings/arm/rockchip/pmu.txt

+Rockchip power-management-unit:
+-------------------------------
+
+The pmu is used to turn off and on different power domains of the SoCs
+This includes the power to the CPU cores.
+
+Required node properties:
+- compatible value : = "rockchip,rk3066-pmu";
+- reg : physical base address and the size of the registers window
+
+Example:
+
+	pmu@20004000 {
+		compatible = "rockchip,rk3066-pmu";
+		reg = <0x20004000 0x100>;
+	};

arch/arm/boot/dts/rk3xxx.dtsi

@@ -31,6 +31,11 @@
 			reg = <0x1013c000 0x100>;
 		};
 
+		pmu@20004000 {
+			compatible = "rockchip,rk3066-pmu";
+			reg = <0x20004000 0x100>;
+		};
+
 		gic: interrupt-controller@1013d000 {
 			compatible = "arm,cortex-a9-gic";
 			interrupt-controller;