[clang][opencl][codegen] Remove the insertion of `correctly-rounded-divide-sqrt-fp-math` fn-attr.

- `-cl-fp32-correctly-rounded-divide-sqrt` is already handled in a
  per-instruction manner by annotating the accuracy required. There's no
  need to add that fn-attr. So far, there's no in-tree backend handling
  that attr and that OpenCL specific option.
- In case that out-of-tree backends are broken, this change could be
  reverted if those backends could not be fixed.

Differential Revision: https://reviews.llvm.org/D88424