ethdev: add new attributes to hairpin config

ethdev: add new attributes to hairpin config

To support two ports hairpin mode and keep the backward compatibility
for the application, two new attribute members of the hairpin queue
configuration structure will be added.

`tx_explicit` means if the application itself will insert the Tx part
flow rules. If not set, PMD will insert the rules implicitly.
`manual_bind` means if the hairpin Tx queue and peer Rx queue will be
bound automatically during the device start stage.

Different Tx and Rx queue pairs could have different values, but it
is highly recommended that all paired queues between one egress and
its peer ingress ports have the same values, in order not to bring
any chaos to the system. The actual support of these attribute
parameters will be checked and decided by the PMD drivers.

In the single port hairpin, if both are zero without any setting, the
behavior will remain the same as before. It means that no bind API
needs to be called and no Tx flow rules need to be inserted manually
by the application.

Signed-off-by: Bing Zhao <bingz@nvidia.com>
Acked-by: Ori Kam <orika@nvidia.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>