i40evf: fix write back with virtual channel 1.1

i40evf: fix write back with virtual channel 1.1

If DPDK is used on VF while the host is using Linux Kernel driver
as PF driver on FVL NIC, then VF Rx is reported only in batches of
4 packets. It is due to the kernel driver assumes VF driver is working
in interrupt mode, but DPDK VF is working in Polling mode.
This patch fixes this issue by using the V1.1 virtual channel with
Linux i40e PF driver.

Signed-off-by: Jingjing Wu <jingjing.wu@intel.com>
Acked-by: Cunming Liang <cunming.liang@intel.com>
Acked-by: Helin Zhang <helin.zhang@intel.com>