net: airoha: Move {cpu,fwd}_tx_packets in airoha_gdm_dev struct

net: airoha: Move {cpu,fwd}_tx_packets in airoha_gdm_dev struct

Since now multiple net_devices connected to different QDMA blocks can
share the same GDM port, cpu_tx_packets and fwd_tx_packets fields can
be overwritten with the value from a different QDMA block. In order to
fix the issue move cpu_tx_packets and fwd_tx_packets fields from
airoha_gdm_port struct to airoha_gdm_dev one.

Tested-by: Xuegang Lu <xuegang.lu@airoha.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20260527-airoha-eth-multi-serdes-preliminary-v1-5-ec6ed73ef7fc@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>