net: airoha: Do not loopback traffic to GDM2 if it is available on the device

net: airoha: Do not loopback traffic to GDM2 if it is available on the device

[ Upstream commit 8e0a754b0836d996802713bbebc87bc1cc17925c ]

Airoha_eth driver forwards offloaded uplink traffic (packets received
on GDM1 and forwarded to GDM{3,4}) to GDM2 in order to apply hw QoS.
This is correct if the device does not support a dedicated GDM2 port.
In this case, in order to enable hw offloading for uplink traffic,
the packets should be sent to GDM{3,4} directly.

Fixes: 9cd451d414f6 ("net: airoha: Add loopback support for GDM2")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20251113-airoha-hw-offload-gdm2-fix-v1-1-7e4ca300872f@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>