!9192 reset the default activation function for bert

From: @shibeiji
Reviewed-by: @c_34,@liangchenghui
Signed-off-by: @c_34

model_zoo/official/nlp/bert/src/config.py

@@ -103,7 +103,7 @@ if cfg.bert_network == 'large':
         num_hidden_layers=24,
         num_attention_heads=16,
         intermediate_size=4096,
-        hidden_act="fast_gelu",
+        hidden_act="gelu",
         hidden_dropout_prob=0.1,
         attention_probs_dropout_prob=0.1,
         max_position_embeddings=512,