d3d9: COM cleanup for the IDirect3DVolumeTexture9 iface.

dlls/d3d9/d3d9_private.h

@@ -350,7 +350,7 @@ HRESULT texture_init(IDirect3DTexture9Impl *texture, IDirect3DDevice9Impl *devic
  */
 typedef struct IDirect3DVolumeTexture9Impl
 {
-    const IDirect3DVolumeTexture9Vtbl *lpVtbl;
+    IDirect3DVolumeTexture9 IDirect3DVolumeTexture9_iface;
     LONG ref;
     struct wined3d_texture *wined3d_texture;
     IDirect3DDevice9Ex *parentDevice;

dlls/d3d9/device.c

@@ -803,7 +803,7 @@ static HRESULT WINAPI IDirect3DDevice9Impl_CreateVolumeTexture(IDirect3DDevice9E
     }
 
     TRACE("Created volume texture %p.\n", object);
-    *texture = (IDirect3DVolumeTexture9 *)object;
+    *texture = &object->IDirect3DVolumeTexture9_iface;
 
     return D3D_OK;
 }