[clang] [SYCL] change sycl version accrodnig to standard (PR #114790)

[Ronan Keryell via cfe-commits]

keryell wrote:

That sounds good.
Could you fix the typos in the PR title and the commit messages.
Please write SYCL in uppercase everywhere since it is a standard name.

https://github.com/llvm/llvm-project/pull/114790