net/virtio: fix Tx completed mbuf leak on device stop
net/virtio: fix Tx completed mbuf leak on device stop

Free Tx completed mbufs on device stop. Not completed Tx mbufs cannot be
freed since they are still in use.

Fixes: c1f86306a026 ("virtio: add new driver")
Cc: stable@dpdk.org

Signed-off-by: Ivan Ilchenko <4969abd0c74f7021df835829a1e4d724acdbdb27@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <4155e7bf8e0185127625dac6d84336299844982f@oktetlabs.ru>
Reviewed-by: Maxime Coquelin <9a2667dee3b90866bbc9c2696cff2b7d5616c95a@redhat.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk