net: ena: ethtool: add stats printing to XDP queues

Added statistics for TX queues that are used for XDP TX. The statistics
are the same as the ones printed for regular non-XDP TX queues.

The XDP queue statistics can be queried using
`ethtool -S <ifname>`

Signed-off-by: Shay Agroskin <shayagr@amazon.com>
Signed-off-by: Sameeh Jubran <sameehj@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>