ARM: mvebu: add enable-method property for CPUs

This commit updates the Armada XP Device Trees (for the three variants
of Armada XP) to declare the "enable-method" property for the CPUs,
which helps operating systems find the appropriate logic to manage the
CPUs, especially to boot secondary CPUs.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483648-26611-4-git-send-email-thomas.petazzoni@free-electrons.comSigned-off-by: Jason Cooper <jason@lakedaemon.net>

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

@@ -27,6 +27,7 @@ aliases {
 	cpus {
 		#address-cells = <1>;
 		#size-cells = <0>;
+		enable-method = "marvell,armada-xp-smp";
 
 		cpu@0 {
 			device_type = "cpu";

arch/arm/boot/dts/armada-xp-mv78260.dtsi

@@ -29,6 +29,7 @@ aliases {
 	cpus {
 		#address-cells = <1>;
 		#size-cells = <0>;
+		enable-method = "marvell,armada-xp-smp";
 
 		cpu@0 {
 			device_type = "cpu";

arch/arm/boot/dts/armada-xp-mv78460.dtsi

@@ -30,6 +30,7 @@ aliases {
 	cpus {
 		#address-cells = <1>;
 		#size-cells = <0>;
+		enable-method = "marvell,armada-xp-smp";
 
 		cpu@0 {
 			device_type = "cpu";