add _repeated_blocks for ErnieImageTransformer2DModel

[kaixuanliu]

This PR fixes failed test case:
tests/models/transformers/test_models_transformer_ernie_image.py::TestErnieImageTransformerCompile::test_torch_compile_repeated_blocks
@yiyixuxu pls help review, thx!

[HuggingFaceDocBuilderDev]

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[dg845]

Thanks for the PR! I think we can remove the pytest.mark.skip decorators from the skipped tests in TestErnieImageTransformerCompile since they all pass after this fix.

[kaixuanliu]

@dg845 Thx for your review, but there is a comment: "The repeated block in this model is ErnieImageSharedAdaLNBlock. As a consequence of this, the inputs recorded for the block would vary during compilation and full compilation with fullgraph=True would trigger recompilation." in L119. Hence I am not sure if it is suitable to remove the pytest.mark.skip decorators here. Maybe @HsiaWinter can give some advice on this?

[dg845]

Merging this PR as I think we can handle the other skipped TestErnieImageTransformerCompile tests separately in a follow-up PR (and the CI failures are unrelated). @HsiaWinter would still be interested in your input as to whether the _repeated_blocks fix in this PR solves the model compile issues (the currently skipped tests pass after the fix).