message: Update mkldnn bf16 type
diff: @@ -32,6 +32,7 @@ precision_map = {
  'int8': paddle_infer.PrecisionType.Int8,
  'fp32': paddle_infer.PrecisionType.Float32,
  'fp16': paddle_infer.PrecisionType.Half,
  + 'bf16': 'bf16',
  }
  @@ -194,6 +195,8 @@ class LocalPredictor(object):
  config.set_cpu_math_library_num_threads(thread_num)
  if use_mkldnn:
  config.enable_mkldnn()
  + if precision_type == "bf16":
  + config.enable_mkldnn_bfloat16()
  if mkldnn_cache_capacity > 0:
  config.set_mkldnn_cache_capacity(mkldnn_cache_capacity)
  if mkldnn_op_list is not None:
  