app/testpmd: do not poll stopped queues

app/testpmd: do not poll stopped queues

Calling Rx/Tx functions on a stopped queue is not supported.
Do not run packet forwarding for streams that use stopped queues.

Each stream has a read-only "disabled" field,
so that lcore function can skip such streams.
Forwarding engines can set this field
using a new "stream_init" callback function
by checking relevant queue states,
which are stored along with queue configurations
(not all PMDs implement rte_eth_rx/tx_queue_info_get()
to query the state from there).

Fixes: 5f4ec54f1d16 ("testpmd: queue start and stop")
Cc: stable@dpdk.org
Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>