remove input_ids = None in qwen2-vl

[Chen-0210]

Motivation

When the logprobs key is included in the request for Qwen2-VL, the server crashes because input_ids is set to None.
The purpose of this line of code is unclear, and it was introduced in PR #2977.

  File "/usr/local/lib/python3.10/dist-packages/sglang/srt/managers/scheduler.py", line 1827, in run_scheduler_process
    scheduler.event_loop_normal()
  File "/usr/local/lib/python3.10/dist-packages/torch/utils/_contextlib.py", line 116, in decorate_context
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.10/dist-packages/sglang/srt/managers/scheduler.py", line 478, in event_loop_normal
    result = self.run_batch(batch)
  File "/usr/local/lib/python3.10/dist-packages/sglang/srt/managers/scheduler.py", line 1080, in run_batch
    logits_output, next_token_ids = self.tp_worker.forward_batch_generation(
  File "/usr/local/lib/python3.10/dist-packages/sglang/srt/managers/tp_worker.py", line 164, in forward_batch_generation
    logits_output = self.model_runner.forward(forward_batch)
  File "/usr/local/lib/python3.10/dist-packages/sglang/srt/model_executor/model_runner.py", line 795, in forward
    return self.forward_extend(forward_batch)
  File "/usr/local/lib/python3.10/dist-packages/sglang/srt/model_executor/model_runner.py", line 760, in forward_extend
    return self.model.forward(
  File "/usr/local/lib/python3.10/dist-packages/sglang/srt/models/qwen2_vl.py", line 570, in forward
    return self.logits_processor(
  File "/usr/local/lib/python3.10/dist-packages/torch/nn/modules/module.py", line 1736, in _wrapped_call_impl
    return self._call_impl(*args, **kwargs)
  File "/usr/local/lib/python3.10/dist-packages/torch/nn/modules/module.py", line 1747, in _call_impl
    return forward_call(*args, **kwargs)
  File "/usr/local/lib/python3.10/dist-packages/sglang/srt/layers/logits_processor.py", line 165, in forward
    pruned_input_ids.append(input_ids[pt + start_len : pt + extend_len])
TypeError: 'NoneType' object is not subscriptable

Modifications

Removed the line.

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[zhaochenyang20]

#3635

@Chen-0210 I combied this in #3635 and will give you credit, thanks for help!