cciss: remove unneeded memset()

The memory return by kzalloc() or kmem_cache_zalloc() has already be set
to zero, so remove useless memset(0).

spatch with a semantic match is used to found this problem.
(http://coccinelle.lip6.fr/)

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Cc: Mike Miller <mike.miller@hp.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/cciss.c

@@ -5205,7 +5205,6 @@ static void cciss_shutdown(struct pci_dev *pdev)
 		return;
 	}
 	/* write all data in the battery backed cache to disk */
-	memset(flush_buf, 0, 4);
 	return_code = sendcmd_withirq(h, CCISS_CACHE_FLUSH, flush_buf,
 		4, 0, CTLR_LUNID, TYPE_CMD);
 	kfree(flush_buf);