[llvm] [OFFLOAD] Fix TARGET_NAME in plugins common code (PR #180151)

[Alex Duran via llvm-commits]

adurang wrote:

> Removing the quotes broke several offload tests. Should be fixed by #180505

Thanks for fixing the tests. I wonder why I didn't get any notification of broken tests :/

https://github.com/llvm/llvm-project/pull/180151