arm: mvebu: Armada XP MV78230 has two cores, not one

Contrary to our understanding at the time armada-xp-mv78230.dtsi was
written, the MV78230 variant of the Armada XP SoC has two cores and
not one. This patch updates the .dtsi file to take into account this
reality.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

arch/arm/boot/dts/armada-xp-mv78230.dtsi

@@ -34,6 +34,13 @@ cpu@0 {
 		reg = <0>;
 		clocks = <&cpuclk 0>;
 	    };
+
+	    cpu@1 {
+		device_type = "cpu";
+		compatible = "marvell,sheeva-v7";
+		reg = <1>;
+		clocks = <&cpuclk 1>;
+	    };
 	}
 
 	soc {