kconfig: Changed default values of bool configs

- Some bool configs were using default values true and false,
  instead of y and n.


* Original commit: espressif/esp-idf@25c5c21

Author: laukik-hase

components/mdns/host_test/components/esp_netif_linux/Kconfig

@@ -2,7 +2,7 @@ menu "LWIP-MOCK-CONFIG"
 
     config LWIP_IPV6
         bool "Enable IPv6"
-        default true
+        default y
         help
             Enable/disable IPv6