drm: free core gem object from driver callbacks

When drivers embed the core gem object into their own structures,
they'll have to do this. Temporarily this results in an ugly

kfree(gem_obj);

in every gem driver.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Eric Anholt <eric@anholt.net>
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 80871c6..d4ea909 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4474,6 +4474,9 @@
 	kfree(obj_priv->page_cpu_valid);
 	kfree(obj_priv->bit_17);
 	kfree(obj->driver_private);
+
+	drm_gem_object_release(obj);
+	kfree(obj);
 }
 
 /** Unbinds all inactive objects. */