[FSDP] Fix bug in determining whether parameters need to be materialized

[jamesr66a]

Previously, _need_to_materialize_module would return false because:

• managed_params =_get_orig_params(module, ignored_params) returns a generator
• is_meta_module = any(param.is_meta for param in managed_params) exhausts the generator in its check
• any(fake.is_fake(param) for param in managed_params) would try to iterate over the empty generator and get an empty sequence, thus returning False

[pytorch-bot]

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[ngimel]

Test?

[awgu]

Great catch! Thanks!

[jamesr66a]

@pytorchbot merge

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