Remove an unused Module param

Summary:
In D65848 the function getFuncNameInModule was refactored to no longer use module.
This diff removes the parameter and rename the function name to avoid confusion.

Reviewers: wenlei, wmi, davidxl

Reviewed By: wenlei

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D79310