Fixes sporadic blocking of the wifi thread in esp_wifi_recv_cb function under heavy network load conditions when frames are coming in faster than they can be processed. Since esp_wifi_recv_cb function is not executed in interrupt context, the msg_send function used for ISR event can block when the message queue is full. With this change esp_wifi can be flooded with icmpv6 packets of maximum size without any problems over hours.
RX callback function should be register when WiFi has been connected to AP successfully and should be unregistered when WiFi disconnects from AP. Therefore, esp_wifi_internal_reg_rxcb is called now in event handler on event SYSTEM_EVENT_STA_CONNECTED. It is reset now on event SYSTEM_EVENT_STA_DISCONNECTED.
Before function wifi_connect is executed, starting the WiFi driver should have been finished. This is indicated by the WiFi driver by sending event SYSTEM_EVENT_STA_START. Function wifi_connect is moved therefore to the event handler for SYSTEM_EVENT_STA_START.
The size of received and transmitted frames was stored in an uint8_t, which did not allow to process frames larger than 255 octets. However, WiFi has an MTU of 1500 octets.
The driver is claiming it is needed for IPv6 / 6LoWPAN support, which
is not true (the long address is never used for NRFMIN in fact) and
this assumption actually leads to an assertion when compiled as with
the `gnrc_border_router` example.
Although ESP32 has four SPI controllers, only two of them can be effectively used (HSP and VSPI). The third one (FSPI) is used for external memory such as flash and PSRAM and can not be used for peripherals. FSPI is therefore removed from the API. In addition, the SPI0_DEV and SPI1_DEV configuration parameters are renamed SPI0_CTRL and SPI1_CTRL to better describe what they define and to avoid confusion with SPI_DEV (0) and SPI_DEV (1).
Although ESP32 has four SPI controllers, only two of them can be effectively used (HSP and VSPI). The third one (FSPI) is used for external memory such as flash and PSRAM and can not be used for peripherals. FSPI is therefore removed from the API. In addition, the SPI0_DEV and SPI1_DEV configuration parameters are renamed SPI0_CTRL and SPI1_CTRL to better describe what they define and to avoid confusion with SPI_DEV (0) and SPI_DEV (1).
Timer restart was moved from esp_now_scan_peers_done to esp_now_scan_peers_start to avoid that the scan for peers isn't triggered anymore if the esp_now_scan_peers_done callback isn't called because of errors.
