This commit removes the usage of all legacy FreeRTOS data types that
are exposed via configENABLE_BACKWARD_COMPATIBILITY. Legacy types can
still be used by enabling CONFIG_FREERTOS_ENABLE_BACKWARD_COMPATIBILITY.
Each esp_netif_next_unsafe() call needs to iterate the s_head list.
It is inefficient with a do-while loop + esp_netif_next_unsafe() call.
Use SLIST_FOREACH instead to simplify the code and speed-up the matching.
While at it, also fix returning NULL from esp_netif_is_netif_listed().
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Darian Leung