[llvm] [Offload][NFC] Re-enable clang-format for omptarget.h (PR #152937)

[Joseph Huber via llvm-commits]

https://github.com/jhuber6 commented:

Why not just enable it for the whole file? All it guards is the enums being aligned by `=` which I think is fine to do without.

https://github.com/llvm/llvm-project/pull/152937