LU-12249 lnet: fix list corruption

LU-12249 lnet: fix list corruption

In shutdown the resend queues are cleared and freed. The monitor
thread state is set to shutdown. It is possible to get lnet_finalize()
called after the queues are freed. The code checks for ln_state to see
if we're shutting down. But in this case we should really be checking
ln_mt_state. The monitor thread is the one that matters in this case,
because it's the one which allocates and frees the resend queues.

Lustre-change: https://review.whamcloud.com/34778
Lustre-commit: d799ac910cd6c980b40c81b76eaefb65b88904d0

Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: Ia077cec7a52ef5cd2e1b231437c6265ba9416b1b
Reviewed-by: Olaf Weber <olaf.weber@hpe.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Chris Horn <hornc@cray.com>
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/36035
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>