In the !VIMAGE_GLOBALS case, make sure not to call vnet_net_iattach()

both via the vnet_mod_register() framework and then directly, but only
once.

Reviewed by:	bz
Approved by:	julian (mentor)

sys/net/if.c

@@ -401,8 +401,9 @@ if_init(void *dummy __unused)
 
 #ifndef VIMAGE_GLOBALS
 	vnet_mod_register(&vnet_net_modinfo);
-#endif
+#else
 	vnet_net_iattach(NULL);
+#endif
 
 	IFNET_LOCK_INIT();
 	ifdev_setbyindex(0, make_dev(&net_cdevsw, 0, UID_ROOT, GID_WHEEL,