Function esp_wifi_internal_get_negotiated_bandwidth 

pub unsafe extern "C" fn esp_wifi_internal_get_negotiated_bandwidth(
    ifx: wifi_interface_t,
    aid: u8,
    bw: *mut u8,
) -> esp_err_t

@brief Get the negotiated bandwidth info after WiFi connection established

@param ifx : WiFi interface @param bw : store the negotiated bandwidth

@return

• ESP_OK: succeed
• ESP_ERR_INVALID_ARG : invalid argument
• ESP_ERR_WIFI_NOT_STARTED : WiFi is not started by esp_wifi_start
• ESP_ERR_WIFI_NOT_CONNECT : No connection between STA and AP