Fix Qwen2.5-Omni get_chunked_index chunking functionality
Author: imkero
Pull request: yes

# What does this PR do?

This PR fixes the incorrect mrope position chunking function `get_chunked_index` in `modular_qwen2_5_omni`. 

> The shape of `token_indices` for `modular_qwen2_5_omni.get_chunked_index` is `(3, seq_len)` in main branch

It takes a constant value `3` (comes from `len(token_indices)`) in the loop condition to iterate the `token_indices` input (instead of the correct value `token_indices.shape[1]`). This will make it always produce only a single chunk. (Line 1160 vs Line 1166)

https://github.com/huggingface/transformers/blob/27a25bee4fcb865e8799ba026f1ea4455f2cca98/src/transformers/models/qwen2_5_omni/modular_qwen2_5_omni.py#L1157-L1168

Another similar but correct impl lies in `processing_qwen2_5_omni` and we can take it as a reference. (Line 303 vs Line 309)

https://github.com/huggingface/transformers/blob/27a25bee4fcb865e8799ba026f1ea4455f2cca98/src/transformers/models/qwen2_5_omni/processing_qwen2_5_omni.py#L300-L311

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@BakerBunker can you take a look about this bugfix please?

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Thank you, I will look at this tomorrow.

LGTM, can be merged after the test cases are passed.

cc @zucchini-nlp 

I think my change on the `spatial_merge_size` config broke some unit tests, will fix them soon.

> I think my change on the `spatial_merge_size` config broke some unit tests, will fix them soon.

The failed tests have been fixed and pass now.

@zucchini-nlp Ready to merge.