!8725 add definition of scale for GPT

From: @alouhahahahaha
Reviewed-by: @guoqi1024,@c_34
Signed-off-by: @guoqi1024

model_zoo/official/nlp/gpt/src/gpt.py

@@ -361,6 +361,7 @@ class Block(nn.Cell):
     """
     def __init__(self, config, layer_idx):
         super(Block, self).__init__()
+        scale = 1.0
         self.layernorm1 = LayerNorm((config.embedding_size,)).to_float(config.compute_dtype)
         self.attention = Attention(config, scale, layer_idx)
         self.layernorm2 = LayerNorm((config.embedding_size,)).to_float(config.compute_dtype)