[clang] [SYCL] Correct incomplete AST visitation for UnresolvedSYCLKernelCallStmt. (PR #185531)

[Erich Keane via cfe-commits]

https://github.com/erichkeane approved this pull request.

Other than the single-line 'if' style nit, this looks fine to me. 

https://github.com/llvm/llvm-project/pull/185531