Enabled LCP echo intervals

Author: Xykon

components/lwip/include/lwip/lwip/opt.h

@@ -2275,7 +2275,7 @@
  * LCP_ECHOINTERVAL: Interval in seconds between keepalive echo requests, 0 to disable.
  */
 #ifndef LCP_ECHOINTERVAL
-#define LCP_ECHOINTERVAL                0
+#define LCP_ECHOINTERVAL                10
 #endif
 
 /**