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/test/dm/cpu.c b/test/dm/cpu.c
index ed12caf..d7e596ee 100644
--- a/test/dm/cpu.c
+++ b/test/dm/cpu.c
@@ -27,7 +27,7 @@
 	     uclass_find_next_device(&dev))
 		ut_assert(dev_get_flags(dev) & DM_FLAG_ACTIVATED);
 
-	ut_assertok(uclass_get_device_by_name(UCLASS_CPU, "cpu-test1", &dev));
+	ut_assertok(uclass_get_device_by_name(UCLASS_CPU, "cpu@1", &dev));
 	ut_asserteq_ptr(cpu_get_current_dev(), dev);
 	ut_asserteq(cpu_is_current(dev), 1);