[RTNETLINK]: Fix sending netlink message when replace route.
When you replace route via ip r r command the netlink multicast message is
not send. This patch corrects it. NL message is sent with NLM_F_REPLACE
flag.
Signed-off-by: Milan Kocian <milon@wq.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>