intel-gtt: introduce drm/intel-gtt.h

Add a few definitions to it that are already shared and that will
be shared in the future (like the number of stolen entries).
No functional changes in here.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
4 files changed