sandbox: correct cpu nodes

The cpu nodes in arch/sandbox/dts/test.dts should conform to the devicetree
specification:

* property device_type must be set to "cpu"
* the reg property must be provided
* the cpu nodes must have an address

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
index 2dfae1c..e27d106 100644
--- a/arch/sandbox/dts/test.dts
+++ b/arch/sandbox/dts/test.dts
@@ -824,19 +824,27 @@
 	};
 
 	cpus {
+		#address-cells = <1>;
+		#size-cells = <0>;
 		timebase-frequency = <2000000>;
-		cpu-test1 {
+		cpu1: cpu@1 {
+			device_type = "cpu";
+			reg = <0x1>;
 			timebase-frequency = <3000000>;
 			compatible = "sandbox,cpu_sandbox";
 			u-boot,dm-pre-reloc;
 		};
 
-		cpu-test2 {
+		cpu2: cpu@2 {
+			device_type = "cpu";
+			reg = <0x2>;
 			compatible = "sandbox,cpu_sandbox";
 			u-boot,dm-pre-reloc;
 		};
 
-		cpu-test3 {
+		cpu3: cpu@3 {
+			device_type = "cpu";
+			reg = <0x3>;
 			compatible = "sandbox,cpu_sandbox";
 			u-boot,dm-pre-reloc;
 		};