Remove all secondary driver private data fields

Now all drivers are converted to use their global state
directly, there is no need for private data fields for
the secondary drivers in virConnectPtr

src/datatypes.h

@@ -350,12 +350,6 @@ struct _virConnect {
      * NB: 'private' is a reserved word in C++.
      */
     void *            privateData;
-    void *            networkPrivateData;
-    void *            interfacePrivateData;
-    void *            storagePrivateData;
-    void *            nodeDevicePrivateData;
-    void *            secretPrivateData;
-    void *            nwfilterPrivateData;
 
     /*
      * The lock mutex must be acquired before accessing/changing