When writev fails to send packets it doesn't update the
number of Tx packets, but it still num_tx is updated.
The value that should be returned is the actual number
of sent packets which is num_packets.
Fixes: 02f96a0a82 ("net/tap: add TUN/TAP device PMD")
CC: stable@dpdk.org
Signed-off-by: Raslan Darawsheh <rasland@mellanox.com>
Acked-by: Keith Wiles <keith.wiles@intel.com>
9396ad3346