xenvm: add a simple PSCI node and a second cpu

Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
CC: rob.herring@calxeda.com
CC: will.deacon@arm.com
CC: arnd@arndb.de

arch/arm/boot/dts/xenvm-4.2.dts

@@ -29,6 +29,19 @@
 			compatible = "arm,cortex-a15";
 			reg = <0>;
 		};
+
+		cpu@1 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a15";
+			reg = <1>;
+		};
+	};
+
+	psci {
+		compatible      = "arm,psci";
+		method          = "hvc";
+		cpu_off         = <1>;
+		cpu_on          = <2>;
 	};
 
 	memory@80000000 {