In re_shutdown() mark interface as down since otherwise we will panic if

interrupt comes in later on, which can happen in some uncommon cases.

Another possible fix is to call re_detach() instead of re_stop(), like
ve(4) does, but I am not sure if the latter is really RTTD, so that stick
with this one-liner for now.

PR:		kern/80005
Approved by:	silence on -arch, no reply from selected network gurus

sys/dev/re/if_re.c

@@ -2490,5 +2490,12 @@ re_shutdown(dev)
 
 	RL_LOCK(sc);
 	re_stop(sc);
+	/*
+	 * Mark interface as down since otherwise we will panic if
+	 * interrupt comes in later on, which can happen in some
+	 * cases. Another option is to call re_detach() instead of
+	 * re_stop(), like ve(4) does.
+	 */
+	sc->rl_ifp->if_flags &= ~IFF_UP;
 	RL_UNLOCK(sc);
 }