commit f5ebec96 upstream.

disconnected_handler works are scheduled on system_wq.
When attempting to unload, first make sure all works
have cleaned up.
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>