With the probe call in our dispatch table, we can now cut away the
last three remaining members in the intel_gtt shared struct and so
remove it completely.

v2: Rebased on top of Daniel's series
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
[danvet: bikeshed commit message a bit.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>