[mlir] [llvm] [OpenMP][MLIR][OMPIRBuilder] Add a small optional constant alloca raise function pass to finalize, utilised in convertTarget (PR #78818)

[via llvm-commits]

agozillon wrote:

Updated PR based on recent comments [(commit)](https://github.com/llvm/llvm-project/pull/78818/commits/f568ba2ab00a42bb5fdc7599ce60f03955605f4e) rebased on recent upstream changes to make sure it remains functional.

Changes made were: 

- Fix badly written comment
- Remove unnecessary function
- remove unrequired llvm:: prefix

Still looking for another reviewer for this PR if possible or further discussion. 

https://github.com/llvm/llvm-project/pull/78818