Logging in series of examples has misuse of "%d" instead of type-appropriate format specifiers.
Fix by changing "%d" to PRIxx macros corresponding to type.
Remove -Wno-format compile flag in those examples that are affected.
esp_netif_init() returns standard esp_err_t error code (unlike tcpip_adapter init), so shall be checked for the return value
Also to make the initialization code more consistent.
