[Mesa-dev] Intel TexImage cleanup

[Eric Anholt]

Only 75 lines of code deletion to offer here.

My goal was to delete the whole CPU upload part of intelTexImage by
moving the mt setup to AllocTextureImageBuffer and using the
MapTextureImage-based Mesa core.  However, because we don't have all
of core converted to MapTextureImage, there are places that call
AllocTextureImageBuffer then immediately expect ->Data to be present,
which we wouldn't be able to provide.