Simplify difference in `clang/test/CodeGenSYCL/loop_unroll.cpp`

[keryell]

I have the feeling that the change at the beginning of should not exist in https://github.com/triSYCL/sycl/compare/8677d5d562bb..6c7fac3aeb6#diff-4decc3bd7c76c920f705a179987a922f7d54b86636121a2cbb4441a7d6ace291

[Ralender]

more than a year ago this was need to make all check-clang tests pass. but I have not tested check-clang in a very long time so maybe there are more errors in check-clang or this changes aren't needed anymore.