ARM: dts: i.MX53: add pmu node

The i.MX53 has a Cortex-A8 Performance Monitor Unit.

Add it to the dtsi.
Signed-off-by: NSteffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: NShawn Guo <shawn.guo@freescale.com>

arch/arm/boot/dts/imx53.dtsi

@@ -747,5 +747,10 @@
 			reg = <0xf8000000 0x20000>;
 			clocks = <&clks IMX5_CLK_OCRAM>;
 		};
+
+		pmu {
+			compatible = "arm,cortex-a8-pmu";
+			interrupts = <77>;
+		};
 	};
 };