net/nfp: cancel delayed LSC work in port close

net/nfp: cancel delayed LSC work in port close

The link state change interrupt handler of the NFP PMD will delay the
actual LSC work for a short period to ensure the link is stable. If the
link of the port changes state and the port is closed immediately after
the link event then a segmentation fault will occur. This happens
because the delayed LSC work eventually triggers and this logic will try
to access private port data that had been released when the port was
closed.

Fixes: 6c53f87b3497 ("nfp: add link status interrupt")
Cc: stable@dpdk.org
Signed-off-by: Heinrich Kuhn <heinrich.kuhn@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>