IPv6 host adds prefixes successfully but return always NULL

In Neighbor Discovery Protocol, when IPv6 host adds a prefix (coming from PIO) but it is always failing whatever if is successfully add in prefix table. The reason comes from the fact that the function uip_ds6_prefix_add in host version always return NULL. This is opposite of the specification of the router version.

core/net/ipv6/uip-ds6.c

@@ -275,6 +275,7 @@ uip_ds6_prefix_add(uip_ipaddr_t *ipaddr, uint8_t ipaddrlen,
     PRINTF("Adding prefix ");
     PRINT6ADDR(&locprefix->ipaddr);
     PRINTF("length %u, vlifetime%lu\n", ipaddrlen, interval);
+    return locprefix;
   }
   return NULL;
 }