Comment 7 for bug 1570466

Xenial is released, so we are back in SRU mode.
Therefore I add the matching SRU Template for the upload of 2.2.0ubuntu8 which is in the unapproved queue atm.

[Impact]

 * without the fix removing guests that were connected to vhost_user ports leaked memory. Thereby a longer running server wich spawned/removed guests over time crashed (openvswitch-dpdk)
 * fix is a backport from upstream to free the device on removal of the active port

[Test Case]

 * create a vhost_user socket in openvswitch-dpdk
 * attach a guest
 * detach the guest
 * loop the three steps above

[Regression Potential]

 * It only frees memory that otherwise would leak and the patch is upstream as well in the meantime (should be pulled fromt he vhost maintainer into main 16.07 soon as well)
 * In testing I found an issue freeing the wrong port if it was uninitialized and improved the patch together with the maintainer
 * passed ADT tests on i368/amd64/amd64-lowmem and our full CI (https://code.launchpad.net/~ubuntu-server/ubuntu/+source/dpdk-testing/+git/dpdk-testing)