Set the default VNET in krping before calling ifunit_ref(). Else usin…

…g IPv6

link-local addresses when VIMAGE is enabled will cause a so-called NULL
pointer dereferencing issue.

Sponsored by:	Mellanox Technologies
MFC after:	1 week

sys/contrib/rdma/krping/krping.c

@@ -3185,7 +3185,9 @@ krping_get_ipv6_scope_id(char *name)
 
 	if (name == NULL)
 		return (0);
+	CURVNET_SET_QUIET(TD_TO_VNET(curthread));
 	ifp = ifunit_ref(name);
+	CURVNET_RESTORE();
 	if (ifp == NULL)
 		return (0);
 	retval = ifp->if_index;