scd4x_i2c_xfer
ret = scd4x_i2c_xfer(state, buf, 2, buf, 0);
ret = scd4x_i2c_xfer(state, buf, 2, buf, response_sz);
ret = scd4x_i2c_xfer(state, buf, SCD4X_WRITE_BUF_SIZE, buf, 0);