[SCSI] remove flush_scheduled_work() usages

Simple conversions to drop flush_scheduled_work() usages in
drivers/scsi.  More involved ones will be done in separate patches.

* NCR5380, megaraid_sas: cancel_delayed_work() +
  flush_scheduled_work() -> cancel_delayed_work_sync().

* mpt2sas_scsih: drop unnecessary flush_scheduled_work().

* arcmsr_hba, ipr, pmcraid: flush the used work explicitly instead of
  using flush_scheduled_work().

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
diff --git a/drivers/scsi/pmcraid.c b/drivers/scsi/pmcraid.c
index 321cf3a..bcf858e 100644
--- a/drivers/scsi/pmcraid.c
+++ b/drivers/scsi/pmcraid.c
@@ -5454,7 +5454,7 @@
 	pmcraid_shutdown(pdev);
 
 	pmcraid_disable_interrupts(pinstance, ~0);
-	flush_scheduled_work();
+	flush_work_sync(&pinstance->worker_q);
 
 	pmcraid_kill_tasklets(pinstance);
 	pmcraid_unregister_interrupt_handler(pinstance);