net/ena: fix per-queue offload capabilities

net/ena: fix per-queue offload capabilities

As ENA currently doesn't support offloads which could be configured
per-queue, only per-port flags should be set.

In addition, to make the code cleaner, parsing appropriate offload
flags is encapsulated into helper functions, in a similar matter it's
done by the other PMDs.

[1] https://doc.dpdk.org/guides/prog_guide/
    poll_mode_drv.html?highlight=offloads#hardware-offload

Fixes: 7369f88f88c0 ("net/ena: convert to new Rx offloads API")
Fixes: 56b8b9b7e5d2 ("net/ena: convert to new Tx offloads API")
Cc: stable@dpdk.org
Signed-off-by: Michal Krawczyk <mk@semihalf.com>
Reviewed-by: Igor Chauskin <igorch@amazon.com>
Reviewed-by: Shai Brandes <shaibran@amazon.com>