drm/etnaviv: Remove duplicate call to drm_gem_free_mmap_offset

The docs explicitly say the drm_gem_object_release function already calls this,
and this does not appear to be a prerequisite for the call to
etnaviv_gem_ops.release.
Signed-off-by: T.J. Mercier <tjmercier@google.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

drivers/gpu/drm/etnaviv/etnaviv_gem.c

@@ -504,7 +504,6 @@ void etnaviv_gem_free_object(struct drm_gem_object *obj)
 		kfree(mapping);
 	}
 
-	drm_gem_free_mmap_offset(obj);
 	etnaviv_obj->ops->release(etnaviv_obj);
 	drm_gem_object_release(obj);