In multi-queue environment testing, the support for VLAN-tag based
steering is useful. So, this patch adds the capability to add
VLAN tag (VLAN ID and Priority) to the generated Tx frame.

To set the VLAN ID=10 and Priority=2 for Tx only through TxQ=3:
 $ xdpsock -i eth0 -t -N -z -q 3 -V -J 10 -K 2

If VLAN ID (-J) and Priority (-K) is set, it default to
  VLAN ID = 1
  VLAN Priority = 0.

For example, VLAN-tagged Tx only, xdp copy mode through TxQ=1:
 $ xdpsock -i eth0 -t -N -c -q 1 -V

Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>

To set Dest MAC address (-G|--tx-dmac) only:
 $ xdpsock -i eth0 -t -N -z -G aa:bb:cc:dd:ee:ff

To set Source MAC address (-H|--tx-smac) only:
 $ xdpsock -i eth0 -t -N -z -H 11:22:33:44:55:66

To set both Dest and Source MAC address:
 $ xdpsock -i eth0 -t -N -z -G aa:bb:cc:dd:ee:ff \
   -H 11:22:33:44:55:66

The default Dest and Source MAC address remain the same as before.

Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>

Tx cycle time is in micro-seconds unit. By combining the batch size (-b M)
and Tx cycle time (-T|--tx-cycle N), xdpsock now can transmit batch-size of
packets every N-us periodically.

For example to transmit 1 packet each 1ms cycle time for total of 2000000
packets:

 $ xdpsock -i eth0 -T -N -z -T 1000 -b 1 -C 2000000

 sock0@enp0s29f1:2 txonly xdp-drv
                   pps            pkts           1.00
rx                 0              0
tx                 1000           1996872

 sock0@enp0s29f1:2 txonly xdp-drv
                   pps            pkts           1.00
rx                 0              0
tx                 1000           1997872

 sock0@enp0s29f1:2 txonly xdp-drv
                   pps            pkts           1.00
rx                 0              0
tx                 1000           1998872

 sock0@enp0s29f1:2 txonly xdp-drv
                   pps            pkts           1.00
rx                 0              0
tx                 1000           1999872

 sock0@enp0s29f1:2 txonly xdp-drv
                   pps            pkts           1.00
rx                 0              0
tx                 128            2000000

 sock0@enp0s29f1:2 txonly xdp-drv
                   pps            pkts           0.00
rx                 0              0
tx                 0              2000000

Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>

When user sets tx-pkt-count and in case where there are invalid Tx frame,
the complete_tx_only_all() process polls indefinitely. So, this patch
adds a time-out mechanism into the process so that the application
can terminate automatically after it retries 3*polling interval duration.

 sock0@enp0s29f1:2 txonly xdp-drv
                   pps            pkts           1.00
rx                 0              0
tx                 136383         1000000
rx dropped         0              0
rx invalid         0              0
tx invalid         35             245
rx queue full      0              0
fill ring empty    0              1
tx ring empty      957            7011

 sock0@enp0s29f1:2 txonly xdp-drv
                   pps            pkts           1.00
rx                 0              0
tx                 0              1000000
rx dropped         0              0
rx invalid         0              0
tx invalid         0              245
rx queue full      0              0
fill ring empty    0              1
tx ring empty      1              7012

 sock0@enp0s29f1:2 txonly xdp-drv
                   pps            pkts           1.00
rx                 0              0
tx                 0              1000000
rx dropped         0              0
rx invalid         0              0
tx invalid         0              245
rx queue full      0              0
fill ring empty    0              1
tx ring empty      1              7013

 sock0@enp0s29f1:2 txonly xdp-drv
                   pps            pkts           1.00
rx                 0              0
tx                 0              1000000
rx dropped         0              0
rx invalid         0              0
tx invalid         0              245
rx queue full      0              0
fill ring empty    0              1
tx ring empty      1              7014

 sock0@enp0s29f1:2 txonly xdp-drv
                   pps            pkts           1.00
rx                 0              0
tx                 0              1000000
rx dropped         0              0
rx invalid         0              0
tx invalid         0              245
rx queue full      0              0
fill ring empty    0              1
tx ring empty      0              7014

 sock0@enp0s29f1:2 txonly xdp-drv
                   pps            pkts           0.00
rx                 0              0
tx                 0              1000000
rx dropped         0              0
rx invalid         0              0
tx invalid         0              245
rx queue full      0              0
fill ring empty    0              1
tx ring empty      0              7014

Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>