Fix warning about keep_dims. keep_dims -> keepdims for tf.reduce_sum(). (#16876)
Fix warning about keep_dims. keep_dims -> keepdims for tf.reduce_sum(). (#16876)

* Fix warning about keep_dims. keep_dims -> keepdims for tf.reduce_sum().

* fix test failure.

tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples