ospf6d: Fix for fast OSPF convergence

Fixed use of OSPF_MIN_LS_ARRIVAL, which changed its unit from
seconds to milliseconds
diff --git a/ospf6d/ospf6_flood.c b/ospf6d/ospf6_flood.c
index 49ed6e2..815db7b 100644
--- a/ospf6d/ospf6_flood.c
+++ b/ospf6d/ospf6_flood.c
@@ -863,7 +863,7 @@
           struct timeval now, res;
           quagga_gettime (QUAGGA_CLK_MONOTONIC, &now);
           timersub (&now, &old->installed, &res);
-          if (res.tv_sec < OSPF_MIN_LS_ARRIVAL)
+          if (res.tv_sec < (OSPF_MIN_LS_ARRIVAL / 1000))
             {
               if (is_debug)
                 zlog_debug ("LSA can't be updated within MinLSArrival, discard");