virt: Register "its" as class property

Class properties make QOM introspection simpler and easier, as
they don't require an object to be instantiated.

Note: "its" is currently registered conditionally, but this makes
the feature be registered unconditionally.  The only side effect
is that it will be now possible to set its=on on virt-2.7 and
older.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20201111183823.283752-7-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

hw/arm/virt.c

@@ -2531,6 +2531,13 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
                                           "Set on/off to enable/disable emulating a "
                                           "guest CPU which implements the ARM "
                                           "Memory Tagging Extension");
+
+    object_class_property_add_bool(oc, "its", virt_get_its,
+                                   virt_set_its);
+    object_class_property_set_description(oc, "its",
+                                          "Set on/off to enable/disable "
+                                          "ITS instantiation");
+
 }
 
 static void virt_instance_init(Object *obj)
@@ -2558,11 +2565,6 @@ static void virt_instance_init(Object *obj)
     } else {
         /* Default allows ITS instantiation */
         vms->its = true;
-        object_property_add_bool(obj, "its", virt_get_its,
-                                 virt_set_its);
-        object_property_set_description(obj, "its",
-                                        "Set on/off to enable/disable "
-                                        "ITS instantiation");
     }
 
     /* Default disallows iommu instantiation */