floppy: don't write kernel-only members to FDRAWCMD ioctl output

Do not leak kernel-only floppy_raw_cmd structure members to userspace.
This includes the linked-list pointer and the pointer to the allocated
DMA space.

Signed-off-by: Matthew Daley <mattd@bugfuzz.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
static int fd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
	int drive = (long)bdev->bd_disk->private_data;
	int type = ITYPE(drive_state[drive].fd_device);
	struct floppy_struct *g;
	int ret;

	ret = get_floppy_geometry(drive, type, &g);
	if (ret)
		return ret;

	geo->heads = g->head;
	geo->sectors = g->sect;
	geo->cylinders = g->track;
	return 0;
}

static int fd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
	int drive = (long)bdev->bd_disk->private_data;
	int type = ITYPE(drive_state[drive].fd_device);
	struct floppy_struct *g;
	int ret;

	ret = get_floppy_geometry(drive, type, &g);
	if (ret)
		return ret;

	geo->heads = g->head;
	geo->sectors = g->sect;
	geo->cylinders = g->track;
	return 0;
}
