dpdk: ipsec tunnel support for ip6-in-ip4

dpdk: ipsec tunnel support for ip6-in-ip4

Type: feature

If an attempt was made to send an IPv6 packet over an IPv4 tunnel,
the DPDK esp_encrypt did not complete setting up
the crypto operation for a buffer, but still queued the crypto
operations that were allocated. This results in a SEGV when
attempting to dequeue them in dpdk-crypto-input.

Allow IPv6 packets to be sent over a v4 tunnel when using the DPDK
plugin esp crypto nodes.

Change-Id: Ic9a4cd69b7fc06a17ab2f64ae806ec2ceacfef27
Signed-off-by: Matthew Smith <mgsmith@netgate.com>