Don't bzero() dp->dad_timer_ch within nd6_dad_start()

[Vitaliy Makkoveev]

It's not required because `dp' was just allocated with M_ZERO flag.

Index: sys/netinet6/nd6_nbr.c
===================================================================
RCS file: /cvs/src/sys/netinet6/nd6_nbr.c,v
retrieving revision 1.138
diff -u -p -r1.138 nd6_nbr.c
--- sys/netinet6/nd6_nbr.c      2 Dec 2022 15:35:35 -0000       1.138
+++ sys/netinet6/nd6_nbr.c      10 Dec 2022 20:41:22 -0000
@@ -1101,7 +1101,6 @@ nd6_dad_start(struct ifaddr *ifa)
                        ifa->ifa_ifp ? ifa->ifa_ifp->if_xname : "???");
                return;
        }
-       bzero(&dp->dad_timer_ch, sizeof(dp->dad_timer_ch));
 
        TAILQ_INSERT_TAIL(&dadq, dp, dad_list);
        ip6_dad_pending++;