cdrom: fix improper type cast, which can leat to information leak.

There is another cast from unsigned long to int which causes
a bounds check to fail with specially crafted input. The value is
then used as an index in the slot array in cdrom_slot_status().

This issue is similar to CVE-2018-16658 and CVE-2018-10940.

Signed-off-by: Young_X <YangX92@hotmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
static noinline int mmc_ioctl_cdrom_start_stop(struct cdrom_device_info *cdi,
					       struct packet_command *cgc,
					       int cmd)
{
	const struct cdrom_device_ops *cdo = cdi->ops;
	cd_dbg(CD_DO_IOCTL, "entering CDROMSTART/CDROMSTOP\n");
	cgc->cmd[0] = GPCMD_START_STOP_UNIT;
	cgc->cmd[1] = 1;
	cgc->cmd[4] = (cmd == CDROMSTART) ? 1 : 0;
	cgc->data_direction = CGC_DATA_NONE;
	return cdo->generic_packet(cdi, cgc);
}

static noinline int mmc_ioctl_cdrom_start_stop(struct cdrom_device_info *cdi,
					       struct packet_command *cgc,
					       int cmd)
{
	const struct cdrom_device_ops *cdo = cdi->ops;
	cd_dbg(CD_DO_IOCTL, "entering CDROMSTART/CDROMSTOP\n");
	cgc->cmd[0] = GPCMD_START_STOP_UNIT;
	cgc->cmd[1] = 1;
	cgc->cmd[4] = (cmd == CDROMSTART) ? 1 : 0;
	cgc->data_direction = CGC_DATA_NONE;
	return cdo->generic_packet(cdi, cgc);
}
