sd: switch to using blk_queue_write_cache()

Switch to the newer interface, instead of using blk_queue_flush()
directly.
Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/sd.c

@@ -137,15 +137,15 @@ static const char *sd_cache_types[] = {
 
 static void sd_set_flush_flag(struct scsi_disk *sdkp)
 {
-	unsigned flush = 0;
+	bool wc = false, fua = false;
 
 	if (sdkp->WCE) {
-		flush |= REQ_FLUSH;
+		wc = true;
 		if (sdkp->DPOFUA)
-			flush |= REQ_FUA;
+			fua = true;
 	}
 
-	blk_queue_flush(sdkp->disk->queue, flush);
+	blk_queue_write_cache(sdkp->disk->queue, wc, fua);
 }
 
 static ssize_t