net: ethernet: ti: am65-cpsw: fix RX & TX statistics for XDP_TX case

For successful XDP_TX and XDP_REDIRECT cases, the packet was received
successfully so update RX statistics. Use original received
packet length for that.

TX packets statistics are incremented on TX completion so don't
update it while TX queueing.

If xdp_convert_buff_to_frame() fails, increment tx_dropped.

Signed-off-by: Roger Quadros <rogerq@kernel.org>
Fixes: 8acacc40 ("net: ethernet: ti: am65-cpsw: Add minimal XDP support")
Link: https://patch.msgid.link/20250210-am65-cpsw-xdp-fixes-v1-2-ec6b1f7f1aca@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>