python,util: Fix SimObjectParams default constructor and destructor (#880)

The empty constructor prevent zero-initialization working correctly. In
this change we fix the issue by removing the unwanted empty constructor.
We also change the default destructor specification with c++11 style.

Change-Id: I869a93ca5283f811c2aa58406f1478459e0d7022

build_tools/sim_object_param_struct_hh.py

@@ -211,8 +211,7 @@ code.indent()
 if sim_object == SimObject:
     code(
         """
-SimObjectParams() {}
-virtual ~SimObjectParams() {}
+virtual ~SimObjectParams() = default;
 
 std::string name;
     """