[libata] Prefer SCSI_SENSE_BUFFERSIZE to sizeof()

Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/libata-scsi.c

@@ -2331,7 +2331,7 @@ static void atapi_request_sense(struct ata_queued_cmd *qc)
 	DPRINTK("ATAPI request sense\n");
 
 	/* FIXME: is this needed? */
-	memset(cmd->sense_buffer, 0, sizeof(cmd->sense_buffer));
+	memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
 
 	ap->ops->tf_read(ap, &qc->tf);