ARM: mvebu: add Device Tree description of USB cluster controller on Armada 375

On Armada 375, the USB cluster allows to control the cluster composed
of the USB2 and USB3 host controllers.

Acked-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1415879269-29711-6-git-send-email-gregory.clement@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

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

@@ -348,6 +348,12 @@
 				#clock-cells = <1>;
 			};
 
+			usbcluster: usb-cluster@18400 {
+				compatible = "marvell,armada-375-usb-cluster";
+				reg = <0x18400 0x4>;
+				#phy-cells = <1>;
+			};
+
 			mbusc: mbus-controller@20000 {
 				compatible = "marvell,mbus-controller";
 				reg = <0x20000 0x100>, <0x20180 0x20>;