net/ena: remove resources when port is being closed

net/ena: remove resources when port is being closed

The new API introduced in 18.11 is suggesting, that the driver should
release all it's resources at the dev_close routine.

All resources previously released in uninit routine during PCI removal,
are now being released at the dev_close and the PMD is indicating that
it is supporting API changes by setting RTE_ETH_DEV_CLOSE_REMOVE flag.

As the device is not allocating MAC addresses dynamically, it is setting
mac_addrs field to NULL, so it wouldn't be released by the
rte_eth_dev_release_port().

Signed-off-by: Michal Krawczyk <mk@semihalf.com>