`spi_device_queue_trans` and `spi_device_get_trans_result` can return `ESP_ERR_TIMEOUT` – but this had not been documented. Merges https://github.com/espressif/esp-idf/pull/1243
`spi_device_queue_trans` and `spi_device_get_trans_result` can return `ESP_ERR_TIMEOUT` – but this had not been documented. Merges https://github.com/espressif/esp-idf/pull/1243