app/testpmd: change hairpin queues setup

app/testpmd: change hairpin queues setup

A new parameter `hairpin-mode` is introduced to the testpmd command
line. Bitmask value is used to provide a more flexible configuration.
This parameter should be used when `hairpinq` is specified in the
command line.

Bit 0 in the LSB indicates the hairpin will use the loop mode. The
previous port Rx queue will be connected to the current port Tx
queue.
Bit 1 in the LSB indicates the hairpin will use pair port mode. The
even index port will be paired with the next odd index port. If the
total number of the probed ports is odd, then the last one will be
paired to itself.
If this byte is zero, then each port will be paired to itself.
Bit 0 takes a higher priority in the checking.

Bit 4 in the second bytes indicate if the hairpin will use explicit
Tx flow mode.

e.g. in the command line, "--hairpinq=2 --hairpin-mode=0x11"

If not set, default value zero will be used and the behavior will
try to get aligned with the previous single port mode. If the ports
belong to different vendors' NICs, it is suggested to use the `self`
hairpin mode only.

Since hairpin configures the hardware resources, the port mask of
packets forwarding engine will not be used here.

Signed-off-by: Bing Zhao <bingz@nvidia.com>
Acked-by: Ori Kam <orika@nvidia.com>