When a device is created with "CREATE" as action, new rings are
allocated for it, then it is a good practice to free them when the
rte_ethdev_dettach method is invoked by the application.
Rings are not freeded when "ATTACH" is used or when the device is
created by means of the rte_eth_from_rings function.
Signed-off-by: Mauricio Vasquez B <mauricio.vasquezbernal@studenti.polito.it>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>