net/ipv6: use configured metric when add peer route

When we add peer address with metric configured, IPv4 could set the dest
metric correctly, but IPv6 do not. e.g.

]# ip addr add 192.0.2.1 peer 192.0.2.2/32 dev eth1 metric 20
]# ip route show dev eth1
192.0.2.2 proto kernel scope link src 192.0.2.1 metric 20
]# ip addr add 2001:db8::1 peer 2001:db8::2/128 dev eth1 metric 20
]# ip -6 route show dev eth1
2001:db8::1 proto kernel metric 20 pref medium
2001:db8::2 proto kernel metric 256 pref medium

Fix this by using configured metric instead of default one.
Reported-by: Jianlin Shi <jishi@redhat.com>
Fixes: 8308f3ff ("net/ipv6: Add support for specifying metric of connected routes")
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -5983,9 +5983,9 @@ static void __ipv6_ifa_notify(int event, struct inet6_ifaddr *ifp)
 		if (ifp->idev->cnf.forwarding)
 			addrconf_join_anycast(ifp);
 		if (!ipv6_addr_any(&ifp->peer_addr))
-			addrconf_prefix_route(&ifp->peer_addr, 128, 0,
-					      ifp->idev->dev, 0, 0,
-					      GFP_ATOMIC);
+			addrconf_prefix_route(&ifp->peer_addr, 128,
+					      ifp->rt_priority, ifp->idev->dev,
+					      0, 0, GFP_ATOMIC);
 		break;
 	case RTM_DELADDR:
 		if (ifp->idev->cnf.forwarding)