i40e HW data is gotten wrongly in i40evf_dev_stop function,
it may cause device can't be stopped.
This patch is to fix the issue.
Fixes: 185993420249 ("net/i40e: fix VF add/del MAC")
Cc: stable@dpdk.org
Signed-off-by: Beilei Xing <beilei.xing@intel.com>