This issue was discovered under the case of software vm2vm
fowarding. When pkts are received from virtio device 0 and
tx_route to virtio device 1, tx of device 0 is not updated.
Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
Tested-by: Qian Xu <qian.q.xu@intel.com>
Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>