ARM: dts: AM33XX: Add PMU support

ARM Performance Monitor Units are available on the am33xx,
add the support in the dtsi.

Tested with perf and oprofile on a regular beaglebone.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Benoit Cousson <bcousson@baylibre.com>

arch/arm/boot/dts/am33xx.dtsi

@@ -57,6 +57,11 @@ cpu@0 {
 		};
 	};
 
+	pmu {
+		compatible = "arm,cortex-a8-pmu";
+		interrupts = <3>;
+	};
+
 	/*
 	 * The soc node represents the soc top level view. It is uses for IPs
 	 * that are not memory mapped in the MPU view or for the MPU itself.