scsi: qedi: Remove redundant flush_workqueue() calls

destroy_workqueue() already drains the queue before destroying it, so there
is no need to flush it explicitly.

Remove the redundant flush_workqueue() calls.

Link: https://lore.kernel.org/r/20220127013934.1184923-1-chi.minghao@zte.com.cn


Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Minghao Chi (CGEL ZTE) <chi.minghao@zte.com.cn>
Signed-off-by: CGEL ZTE <cgel.zte@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>