Enable fixed fast_mode for complex (#55699)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/55699
Todo:
- error message should be updated to say whether the failure is for fn's real or imaginary component
Test Plan: Imported from OSS
Reviewed By: H-Huang
Differential Revision: D28007887
Pulled By: soulitzer
fbshipit-source-id: 1819201f59c8586a1d9631db05983969438bde66
