net/i40e: fix dropping packets with ethertype 0x88A8

net/i40e: fix dropping packets with ethertype 0x88A8

In FW default settings, Ethertype 0x88A8 is treated as S-TAG,
and packets with S-TAG should be received in Port Virtualizer mode.
However, Port Virtualizer mode is not initialized in DPDK, so X710 will
drop packets with Ethertype 0x88A8.
This patch fixes this issue by turning off S-TAG identification.

Fixes: 4861cde46116 ("i40e: new poll mode driver")

Signed-off-by: Beilei Xing <beilei.xing@intel.com>
Acked-by: Jingjing Wu <jingjing.wu@intel.com>