Documentation: devicetree: arm: sort enable-method entries

People have appended new entries instead of inserting them at
the right location, so sort them.
Signed-off-by: NOlof Johansson <olof@lixom.net>

Documentation/devicetree/bindings/arm/cpus.txt

@@ -178,18 +178,18 @@ nodes to be present and contain the properties described below.
 		Usage and definition depend on ARM architecture version.
 			# On ARM v8 64-bit this property is required and must
 			  be one of:
-			     "spin-table"
 			     "psci"
+			     "spin-table"
 			# On ARM 32-bit systems this property is optional and
 			  can be one of:
-			    "arm,psci"
 			    "allwinner,sun6i-a31"
-			    "qcom,gcc-msm8660"
-			    "qcom,kpss-acc-v1"
-			    "qcom,kpss-acc-v2"
+			    "arm,psci"
 			    "marvell,armada-375-smp"
 			    "marvell,armada-380-smp"
 			    "marvell,armada-xp-smp"
+			    "qcom,gcc-msm8660"
+			    "qcom,kpss-acc-v1"
+			    "qcom,kpss-acc-v2"
 			    "rockchip,rk3066-smp"
 
 	- cpu-release-addr