GRO stores packets as fraglist. If they are routed back to the ethernet
device, they need to be re-segmented if the driver does not support
sending fraglists.
Add the missing support for that, along with a missing feature flag that
allows full routed GRO->TSO offload.
Considerably reduces CPU utilization for routing
Signed-off-by: Felix Fietkau <nbd@nbd.name>
9a4253b81f