Revert "wined3d: Preload target in ActivateContext() for ORM_BACKBUFFER/ORM_PBUFFER."

[Stefan Dösinger]

> It could be different - I can't tell for sure. This game doesn't
> produce any
> reasonable crash dump, just a message that it crashed (so not even
> winedbg's
> output). However the problems start with call to... Preload.
Vertexbuffer::PreLoad has nothing in common with Surface::PreLoad or
Texture::PreLoad, other than that the name(since they inherit from
Resource::PreLoad, which is a No-op)