Function esp_idf_sys::uart_flush_input

pub unsafe extern "C" fn uart_flush_input(uart_num: uart_port_t) -> esp_err_t

@brief Clear input buffer, discard all the data is in the ring-buffer. @note In order to send all the data in tx FIFO, we can use uart_wait_tx_done function. @param uart_num UART_NUM_0, UART_NUM_1 or UART_NUM_2

@return - ESP_OK Success - ESP_FAIL Parameter error