drm/i915: Rename drm_gem_object_unreference in preparation for lockless free

Ultimately wraps kref_put(), so adopt its nomenclature for consistency
with other subsystems.

s/drm_gem_object_unreference/i915_gem_object_put/

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469005202-9659-6-git-send-email-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469017917-15134-5-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index c41bf74..cd4af22 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -119,7 +119,7 @@
 		dev_priv->mm.interruptible = was_interruptible;
 	}
 
-	drm_gem_object_unreference(&obj->base);
+	i915_gem_object_put(obj);
 	mutex_unlock(&dev->struct_mutex);
 }
 
@@ -577,7 +577,7 @@
 	}
 
 	obj->userptr.workers--;
-	drm_gem_object_unreference(&obj->base);
+	i915_gem_object_put(obj);
 	mutex_unlock(&dev->struct_mutex);
 
 	release_pages(pvec, pinned, 0);