openvswitch: Set mark and labels before confirming.

Set conntrack mark and labels right before committing so that
the initial conntrack NEW event has the mark and labels.

Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Acked-by: Joe Stringer <joe@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>