[non-strict export] support tensor attribute without other args (#121176)
Summary: Without args we have a hard time detecting fake modes. This causes a fake mode mismatch error in non-strict (specifically, `aot_export_module`) when the module contains tensor attributes, because we create a fresh fake mode when we cannot detect one. The fix is to pass the same fake mode throughout.
Test Plan: added test
Differential Revision: D54516595
Pull Request resolved: https://github.com/pytorch/pytorch/pull/121176
Approved by: https://github.com/angelayi, https://github.com/tugsbayasgalan
