Prove that reap is done correctly on port stop

Make sure that PMD is able to free all remaining mbufs connected with any of descriptors pending on port stop

The test is to verify that PMD is able to free mbufs involved in transmission in case if port stop occurs

1. Obtain the source Ethernet address

2. Adjust the traffic template

3. Initialize the Ethernet device to get its capabilities

4. Enable Tx multi-segment offload if supported

5. Configure the Ethernet device and setup its Rx queues

6. Setup the Ethernet device Tx queues

7. Start the Ethernet device and wait for link up

8. Set up a mempool (or multiple mempool instances)

9. Ensure that interface is UP on Tester side

10. Generate packets and send them in bursts

11. Stop the Ethernet device

12. Make sure that all the objects within the mempool are free

Parameters:

template	Traffic template
multi_mempool	If TRUE, multiple mempools will be created for building mbuf chains from randomly sized segments pulled out of those pools provided that the feature is supported by the transmit datapath
update_refcnt	Pktmbuf reference counter toggle used to activate reap operation check with respect to packets which shall not be released upon a Tx burst or port stop
ring_size_multiplier	An integer multiplier of Tx ring size used to compute the number of packets

reap_on_stop