[ESIMD] Fix - inconsistent 'is_one_of_t' declaration (#6927)

Author: dongkyunahn-intel

sycl/include/sycl/ext/intel/experimental/esimd/common.hpp

@@ -214,7 +214,7 @@ enum class cache_hint : uint8_t {
 namespace detail {
 
 template <cache_hint Hint> class cache_hint_wrap {
-  template <cache_hint...> class is_one_of_t;
+  template <cache_hint...> struct is_one_of_t;
   template <cache_hint Last>
   struct is_one_of_t<Last>
       : std::conditional<Last == Hint, std::true_type, std::false_type>::type {