sycl-ref: remove redundant NULL guards on sycl::free calls

SYCL spec §4.8.3.6 guarantees sycl::free(nullptr, ctx) is a no-op,
matching the behavior of std::free(NULL). The NULL checks on
d_array_owned and reduction_norm are unnecessary.

Author: pvelesko

backends/sycl-ref/ceed-sycl-vector.sycl.cpp

@@ -691,8 +691,8 @@ static int CeedVectorDestroy_Sycl(const CeedVector vec) {
   CeedCallBackend(CeedGetData(ceed, &data));
 
   CeedCallSycl(ceed, data->sycl_queue.wait_and_throw());
-  if (impl->d_array_owned) CeedCallSycl(ceed, sycl::free(impl->d_array_owned, data->sycl_context));
-  if (impl->reduction_norm) CeedCallSycl(ceed, sycl::free(impl->reduction_norm, data->sycl_context));
+  CeedCallSycl(ceed, sycl::free(impl->d_array_owned, data->sycl_context));
+  CeedCallSycl(ceed, sycl::free(impl->reduction_norm, data->sycl_context));
 
   CeedCallBackend(CeedFree(&impl->h_array_owned));
   CeedCallBackend(CeedFree(&impl));