extmod/modussl_mbedtls: Allow to build with object representation D.

extmod/modussl_mbedtls.c

@@ -334,7 +334,7 @@ STATIC mp_obj_t mod_ssl_wrap_socket(size_t n_args, const mp_obj_t *pos_args, mp_
         { MP_QSTR_key, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
         { MP_QSTR_cert, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
         { MP_QSTR_server_side, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
-        { MP_QSTR_server_hostname, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
+        { MP_QSTR_server_hostname, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_PTR(&mp_const_none_obj)} },
         { MP_QSTR_do_handshake, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = true} },
     };