Function esp_wifi_internal_reg_rxcb 

pub unsafe extern "C" fn esp_wifi_internal_reg_rxcb(
    ifx: u32,
    fn_: Option<unsafe extern "C" fn(*mut c_void, u16, *mut c_void) -> i32>,
) -> i32

@brief Set the WiFi RX callback

@attention 1. Currently we support only one RX callback for each interface

@param wifi_interface_t ifx : interface @param wifi_rxcb_t fn : WiFi RX callback

@return - ESP_OK : succeed - others : fail