openvswitch: Respect conntrack zone even if invalid

If userspace executes ct(zone=1), and the connection tracker determines
that the packet is invalid, then the ct_zone flow key field is populated
with the default zone rather than the zone that was specified. Even
though connection tracking failed, this field should be updated with the
value that the action specified. Fix the issue.

Fixes: 7f8a436e ("openvswitch: Add conntrack action")
Signed-off-by: Joe Stringer <joe@ovn.org>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>