ipvs: fix ARP resolving for direct routing mode

ipvs: fix ARP resolving for direct routing mode

[ Upstream commit ad4d3ef8b7eb527cca478dc08c02c10936e64115 ]

After the change "Make neigh lookups directly in output packet path"
(commit a263b30936) IPVS can not reach the real server for DR mode
because we resolve the destination address from IP header, not from
route neighbour. Use the new FLOWI_FLAG_KNOWN_NH flag to request
output routes with known nexthop, so that it has preference
on resolving.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>