Fix load_model_dict_into_meta for ControlNet from_single_file

[DN6]

What does this PR do?

Small fix for load_model_dict_into_meta in ControlNet single file loading. It is using torch_dtype instead of dtype

Fixes # (issue)

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[yiyixuxu]

ahhh my bad!!!
do we not have a single test for controlnet from_single_file? I think I broke it completely

(i see... it is slow tests only....)

[HuggingFaceDocBuilderDev]

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[DN6]

We don't have fast tests. But we're working on it. See #6961