Moves render target restoring to RestoreAPIState, this also means no need
to manually restore after allocating in a buffer that caused execution,
because the manager restores it for us.
Remove a method that wasn't used from D3DUtil.cpp, and fixes a few errors
in EFB poke drawing.
This is not optimal, but for those texture packs with extremely large
images, it won't crash. Releasing after the frame completes is an option
too, however, there is the risk of running out of memory by doing this.
Léo Lam