This table contains all the FC IDs that have recently
been released. So it lists all the FC IDs that have
valid WWN to FC ID mappings and currently not assigned
to any ports. These FC ID were assigned to ports and now,
have been released. This cached FC ID contains only Area
ID and Port ID information. The FC ID cache is kept to
provide best effort re-assignment of same FC IDs. i.e,
an Nx_port would get the same FC ID when it asks for a FC
ID again, after releasing it.