drm: kill drm_mm_node->private

Only ever assigned, never used.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
[glisse: I will re-add if needed for range-restricted allocations]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0743858..75061b3 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2633,10 +2633,8 @@
 	if (free_space != NULL) {
 		obj_priv->gtt_space = drm_mm_get_block(free_space, obj->size,
 						       alignment);
-		if (obj_priv->gtt_space != NULL) {
-			obj_priv->gtt_space->private = obj;
+		if (obj_priv->gtt_space != NULL)
 			obj_priv->gtt_offset = obj_priv->gtt_space->start;
-		}
 	}
 	if (obj_priv->gtt_space == NULL) {
 		/* If the gtt is empty and we're still having trouble