net: Add extack to validator_info structs used for address notifier

Add extack to in_validator_info and in6_validator_info. Update the one
user of each, ipvlan, to return an error message for failures.

Only manual configuration of an address is plumbed in the IPv6 code path.

Signed-off-by: David Ahern <dsahern@gmail.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index 751d051..681dff3 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -154,6 +154,7 @@ struct in_ifaddr {
 struct in_validator_info {
 	__be32			ivi_addr;
 	struct in_device	*ivi_dev;
+	struct netlink_ext_ack	*extack;
 };
 
 int register_inetaddr_notifier(struct notifier_block *nb);