ARM: dts: add PMU to the NHK15 device tree

The so-called Nomadik Power Mangament Unit is actually a set
of some power management registers and some miscellaneous
system control stuff like muxing of entire hardware units.
Add this as a system controller.
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

arch/arm/boot/dts/ste-nomadik-stn8815.dtsi

@@ -168,6 +168,12 @@
 		};
 	};
 
+	/* Power Management Unit */
+	pmu: pmu@101e9000 {
+		compatible = "stericsson,nomadik-pmu", "syscon";
+		reg = <0x101e0000 0x1000>;
+	};
+
 	src: src@101e0000 {
 		compatible = "stericsson,nomadik-src";
 		reg = <0x101e0000 0x1000>;