vmxnet3: correctly report gso type for UDP tunnels

vmxnet3: correctly report gso type for UDP tunnels

Commit 3d010c8031e3 ("udp: do not accept non-tunnel GSO skbs landing
in a tunnel") added checks in linux stack to not accept non-tunnel
GRO packets landing in a tunnel. This exposed an issue in vmxnet3
which was not correctly reporting GRO packets for tunnel packets.

This patch fixes this issue by setting correct GSO type for the
tunnel packets.

Currently, vmxnet3 does not support reporting inner fields for LRO
tunnel packets. The issue is not seen for egress drivers that do not
use skb inner fields. The workaround is to enable tnl-segmentation
offload on the egress interfaces if the driver supports it. This
problem pre-exists this patch fix and can be addressed as a separate
future patch.

Fixes: dacce2be3312 ("vmxnet3: add geneve and vxlan tunnel offload support")
Signed-off-by: Ronak Doshi <ronak.doshi@broadcom.com>
Acked-by: Guolin Yang <guolin.yang@broadcom.com>
Link: https://patch.msgid.link/20250530152701.70354-1-ronak.doshi@broadcom.com
[pabeni@redhat.com: dropped the changelog]
Signed-off-by: Paolo Abeni <pabeni@redhat.com>