ARM: mvebu: Enable Performance Monitor Unit on Armada 375 SoC

The Armada 375 SoC has a Cortex-A9 CPU, and so the PMU is available
to be used. This commit enables it in the devicetree.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

arch/arm/boot/dts/armada-375.dtsi

@@ -96,6 +96,11 @@
 		};
 	};
 
+	pmu {
+		compatible = "arm,cortex-a9-pmu";
+		interrupts-extended = <&mpic 3>;
+	};
+
 	soc {
 		compatible = "marvell,armada375-mbus", "simple-bus";
 		#address-cells = <2>;