net/ice/base: fix PPPoE-IPv6 dummy packet

net/ice/base: fix PPPoE-IPv6 dummy packet

The dummy packet for pppoe-ipv6 has an error, we should
use 0x3b for next header in ipv6 header in the dummy packet,
or some case can not be download, such as:

"eth / pppoes seid is 3 / pppoe_proto_id is 0x0057 /
end actions vf id 1 / end"

Fixes: 55d61fb27a5e ("net/ice/base: add PPPoE IPv6 dummy packet")

Signed-off-by: Wei Zhao <wei.zhao1@intel.com>
Tested-by: Nannan Lu <nannan.lu@intel.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>