[icmpv6] fix resource leak of icmpv6

Signed-off-by: meijian <meijian@xiaomi.com>

net/icmpv6/icmpv6_autoconfig.c

@@ -392,6 +392,12 @@ got_lladdr:
       ret = icmpv6_send_message(dev, false);
       if (ret < 0)
         {
+          /* Remove our wait structure from the list (we may no longer be
+           *  at the head of the list).
+           */
+
+          icmpv6_rwait_cancel(&notify);
+
           nerr("ERROR: Failed send router solicitation: %d\n", ret);
           break;
         }