ec_params_i2c_passthru_msg
size += num * sizeof(struct ec_params_i2c_passthru_msg);
num * sizeof(struct ec_params_i2c_passthru_msg);
struct ec_params_i2c_passthru_msg *msg = ¶ms->msg[i];
struct ec_params_i2c_passthru_msg msg[];