eth: fbnic: Report XDP stats via ethtool

Add support to collect XDP stats via ethtool API. We record
packets and bytes sent, and packets dropped on the XDP_TX path.

ethtool -S eth0 | grep xdp | grep -v "0"
     xdp_tx_queue_13_packets: 2
     xdp_tx_queue_13_bytes: 16126

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Mohsin Bashir <mohsin.bashr@gmail.com>
Link: https://patch.msgid.link/20250813221319.3367670-10-mohsin.bashr@gmail.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>