added comment, fixed coding style

src/core/ipv6/nd6.c

@@ -1843,6 +1843,11 @@ nd6_reachability_hint(const ip6_addr_t * ip6addr)
 }
 #endif /* LWIP_ND6_TCP_REACHABILITY_HINTS */
 
+/**
+ * Remove all prefix, neighbor_cache and router entries of the specified netif.
+ *
+ * @param netif points to a network interface
+ */
 void
 nd6_cleanup_netif(struct netif * netif)
 {

src/netif/etharp.c

@@ -585,7 +585,8 @@ etharp_remove_static_entry(const ip4_addr_t *ipaddr)
  *
  * @param netif points to a network interface
  */
-void etharp_cleanup_netif(struct netif *netif)
+void
+etharp_cleanup_netif(struct netif *netif)
 {
   u8_t i;