ipvs: inherit forwarding method in backup

 	Connections in backup server should inherit the
forwarding method from real server. It is a way to fix a
problem where the forwarding method in backup connection
is damaged by logical OR operation with the real server's
connection flags. And the change is needed for setups
where the backup server uses different forwarding method
for the same real servers.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>