Del self in GenerationMixin. (#746)

Del self in GenerationMixin.

Author: jm12138

paddlenlp/transformers/generation_utils.py

@@ -287,7 +287,7 @@ def prepare_attention_mask_for_generation(input_ids, pad_token_id,
         is_pad_token_not_equal_to_eos_token_id = (eos_token_id is None) or (
             (eos_token_id is not None) and (pad_token_id != eos_token_id))
         if is_pad_token_in_inputs_ids and is_pad_token_not_equal_to_eos_token_id:
-            attention_mask = (input_ids == self.pad_token_id
+            attention_mask = (input_ids == pad_token_id
                               ).astype(paddle.get_default_dtype()) * -1e9
         else:
             attention_mask = paddle.zeros_like(