d3d8: COM cleanup for the IDirect3DVolumeTexture8 iface.

dlls/d3d8/d3d8_private.h

@@ -378,8 +378,8 @@ HRESULT texture_init(IDirect3DTexture8Impl *texture, IDirect3DDevice8Impl *devic
  */
 struct IDirect3DVolumeTexture8Impl
 {
-    const IDirect3DVolumeTexture8Vtbl *lpVtbl;
-    LONG                   ref;
+    IDirect3DVolumeTexture8 IDirect3DVolumeTexture8_iface;
+    LONG ref;
     IWineD3DBaseTexture *wined3d_texture;
     IDirect3DDevice8 *parentDevice;
 };

dlls/d3d8/device.c

@@ -739,7 +739,7 @@ static HRESULT WINAPI IDirect3DDevice8Impl_CreateVolumeTexture(IDirect3DDevice8
     }
 
     TRACE("Created volume texture %p.\n", object);
-    *texture = (IDirect3DVolumeTexture8 *)object;
+    *texture = &object->IDirect3DVolumeTexture8_iface;
 
     return D3D_OK;
 }