Fix atomic stores for 16-bit types (AdaptiveCpp#1881)

Author: illuhad

include/hipSYCL/sycl/libkernel/sscp/atomic_builtins.hpp

@@ -38,7 +38,7 @@ HIPSYCL_BUILTIN void __acpp_atomic_store(T *addr, T x, memory_order order,
   } else if constexpr (sizeof(T) == 2) {
     __acpp_sscp_atomic_store_i16(S, order, scope,
                                     reinterpret_cast<__acpp_int16 *>(addr),
-                                    __builtin_bit_cast(__acpp_int8, x));
+                                    __builtin_bit_cast(__acpp_int16, x));
   } else if constexpr (sizeof(T) == 4) {
     __acpp_sscp_atomic_store_i32(S, order, scope,
                                     reinterpret_cast<__acpp_int32 *>(addr),