drm: Constify the drm_mm API

Mark up the pointers as constant through the API where appropriate.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161216074718.32500-5-chris@chris-wilson.co.uk
3 files changed