scsi: arcmsr: Send SYNCHRONIZE_CACHE command to firmware

BugLink: http://bugs.launchpad.net/bugs/1642572

commit 2bf7dc84 upstream.

The arcmsr driver failed to pass SYNCHRONIZE CACHE to controller
firmware. Depending on how drive caches are handled internally by
controller firmware this could potentially lead to data integrity
problems.

Ensure that cache flushes are passed to the controller.

[mkp: applied by hand and removed unused vars]
Signed-off-by: Ching Huang <ching2048@areca.com.tw>
Reported-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/scsi/arcmsr/arcmsr_hba.c

@@ -2636,18 +2636,9 @@ static int arcmsr_queue_command_lck(struct scsi_cmnd *cmd,
 	struct AdapterControlBlock *acb = (struct AdapterControlBlock *) host->hostdata;
 	struct CommandControlBlock *ccb;
 	int target = cmd->device->id;
-	int lun = cmd->device->lun;
-	uint8_t scsicmd = cmd->cmnd[0];
 	cmd->scsi_done = done;
 	cmd->host_scribble = NULL;
 	cmd->result = 0;
-	if ((scsicmd == SYNCHRONIZE_CACHE) ||(scsicmd == SEND_DIAGNOSTIC)){
-		if(acb->devstate[target][lun] == ARECA_RAID_GONE) {
-    			cmd->result = (DID_NO_CONNECT << 16);
-		}
-		cmd->scsi_done(cmd);
-		return 0;
-	}
 	if (target == 16) {
 		/* virtual device for iop message transfer */
 		arcmsr_handle_virtual_command(acb, cmd);