sfc: correctly advertise tunneled IPv6 segmentation

sfc: correctly advertise tunneled IPv6 segmentation

Recent sfc NICs are TSO capable for some tunnel protocols. However, it
was not working properly because the feature was not advertised in
hw_enc_features, but in hw_features only.

Setting up a GENEVE tunnel and using iperf3 to send IPv4 and IPv6 traffic
to the tunnel show, with tcpdump, that the IPv4 packets still had ~64k
size but the IPv6 ones had only ~1500 bytes (they had been segmented by
software, not offloaded). With this patch segmentation is offloaded as
expected and the traffic is correctly received at the other end.

Fixes: 24b2c3751aa3 ("sfc: advertise encapsulated offloads on EF10")
Reported-by: Tianhao Zhao <tizhao@redhat.com>
Signed-off-by: Íñigo Huguet <ihuguet@redhat.com>
Acked-by: Martin Habets <habetsm.xilinx@gmail.com>
Link: https://lore.kernel.org/r/20230125143513.25841-1-ihuguet@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>