Fix double free in af_packet api/cli

Fix double free in af_packet api/cli

The api was allocating a vector for the name, passing it, then freeing
it, on create. The cli allocated, passed then forgot about it.

af_packet_create_if was storing a reference to the name, which in the
case of the api, meant it was referencing dead memory. On
af_packet_delete_if this reference was freed, so in the api case, there
was a double free.

Also, the cli for delete leaked the name.

Change-Id: I4d572bd2936eaf8ea7a0a8ff282e83ac2bf1b062
Signed-off-by: Ivan Kelly <ivan@midokura.com>