nd6: Zap nd6_recalc_reachtm_interval indirection

[Klemens Nanni]

Only used once, so use the macro directly like ND6_SLOWTIMER_INTERVAL
is used in many places.

OK?

diff --git a/sys/netinet6/nd6.c b/sys/netinet6/nd6.c
index ff679bcb151..3decec947c4 100644
--- a/sys/netinet6/nd6.c
+++ b/sys/netinet6/nd6.c
@@ -88,8 +88,6 @@ TAILQ_HEAD(llinfo_nd6_head, llinfo_nd6) nd6_list;
 struct pool nd6_pool;          /* pool for llinfo_nd6 structures */
 int    nd6_inuse;
 
-int nd6_recalc_reachtm_interval = ND6_RECALC_REACHTM_INTERVAL;
-
 void nd6_timer(void *);
 void nd6_slowtimo(void *);
 void nd6_expire(void *);
@@ -1318,7 +1316,7 @@ nd6_slowtimo(void *ignored_arg)
                         * value gets recomputed at least once every few hours.
                         * (RFC 2461, 6.3.4)
                         */
-                       nd6if->recalctm = nd6_recalc_reachtm_interval;
+                       nd6if->recalctm = ND6_RECALC_REACHTM_INTERVAL;
                        nd6if->reachable = 
ND_COMPUTE_RTIME(nd6if->basereachable);
                }
        }