use void for highest to match template candidates

src/targets/gpu/kernels/include/migraphx/kernels/float8.hpp

@@ -32,8 +32,8 @@
 #define MIGRAPHX_F8_DOWNCAST_CLIPPING 1 // NOLINT
 
 #include <migraphx/kernels/types.hpp>
-#include <migraphx/kernels/float8_impl.hpp>
 #include <migraphx/kernels/type_traits.hpp>
+#include <migraphx/kernels/float8_impl.hpp>
 
 namespace migraphx {
 namespace fp8 {

src/targets/gpu/kernels/include/migraphx/kernels/math.hpp

@@ -25,11 +25,11 @@
 #define MIGRAPHX_GUARD_KERNELS_MATH_HPP
 
 #include <migraphx/kernels/types.hpp>
-#include <migraphx/kernels/float8.hpp>
 #include <migraphx/kernels/vec.hpp>
 #include <migraphx/kernels/functional.hpp>
 #include <migraphx/kernels/type_traits.hpp>
 #include <migraphx/kernels/hip.hpp>
+#include <migraphx/kernels/float8.hpp>
 
 namespace migraphx {
 

src/targets/gpu/kernels/include/migraphx/kernels/ops.hpp

@@ -118,7 +118,7 @@ struct highest
     template <class T>
     constexpr operator T() const
     {
-        return numeric_max<vec_type<T>>();
+        return numeric_max<vec_type<T>, void>();
     }
 };
 } // namespace migraphx