if_detach(): move nd6_ifdetach() out of netlock

[Vitaliy Makkoveev]

In this point, the interface is disconnected from everywhere. No need to
hold netlock for dummy 'nd_ifinfo' release. Netlock is also not needed
for TAILQ_EMPTY(&ifp->if_*hooks) assertions.

Index: sys/net/if.c
===================================================================
RCS file: /cvs/src/sys/net/if.c,v
retrieving revision 1.699
diff -u -p -r1.699 if.c
--- sys/net/if.c        5 Jun 2023 11:35:46 -0000       1.699
+++ sys/net/if.c        7 Jun 2023 10:15:12 -0000
@@ -1170,6 +1170,8 @@ if_detach(struct ifnet *ifp)
                        ifafree(ifa);
                }
        }
+       splx(s);
+       NET_UNLOCK();
 
        KASSERT(TAILQ_EMPTY(&ifp->if_addrhooks));
        KASSERT(TAILQ_EMPTY(&ifp->if_linkstatehooks));
@@ -1178,8 +1180,6 @@ if_detach(struct ifnet *ifp)
 #ifdef INET6
        nd6_ifdetach(ifp);
 #endif
-       splx(s);
-       NET_UNLOCK();
 
        /* Announce that the interface is gone. */
        rtm_ifannounce(ifp, IFAN_DEPARTURE);