[SYCL][NFC] Fix warning caused by inconsistent struct/class usage for Builder

Signed-off-by: Vyacheslav N Klochkov <[email protected]>

Author: v-klochkov

sycl/include/CL/sycl/item.hpp

@@ -77,7 +77,7 @@ template <int dimensions = 1, bool with_offset = true> class item {
        const id<dimensions> &index)
       : MImpl{extent, index} {}
 
-  friend struct detail::Builder;
+  friend class detail::Builder;
 
 private:
   detail::ItemBase<dimensions, with_offset> MImpl;