[clang] [Driver][NFC] Show SYCL support in -Xarch_device/host help text (PR #165503)

[via cfe-commits]

jinge90 wrote:

Hi, @bader 
-Xarch_device/host can work for SYCL and we have used them in intel/llvm, this PR shows SYCL is supported in -Xarch_device/host help text.
Thanks very much.

https://github.com/llvm/llvm-project/pull/165503