[Code Simplification] delete cum_offsets_out (PaddlePaddle#3815)

* fix

* fix

Author: lizexu123

custom_ops/gpu_ops/speculate_decoding/speculate_get_padding_offset.cu

@@ -139,6 +139,7 @@ std::vector<paddle::DataType> SpeculateGetPaddingOffsetInferDtype(
 PD_BUILD_STATIC_OP(speculate_get_padding_offset)
     .Inputs({"input_ids",
              "draft_tokens",
+             "cum_offsets"
              "token_num",
              "seq_len",
              "seq_lens_encoder"})