message: Remove incorrect comment for enable_v2_dtype_behavior().
  The comment stated the function would be removed soon, but there are no plans on removing it. It is useful for users who wish to use mixed precision while still running with mostly V1 behavior by calling tf.compat.v1.disable_v2_behavior().
diff: @@ -658,8 +658,6 @@ def mark_as_return(outputs, acd):
  V2_DTYPE_BEHAVIOR = None
  -# These two functions are not exported because we plan on removing them in the
  -# future.
  def enable_v2_dtype_behavior():
  """Enable the V2 dtype behavior for Keras layers.
  