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 transfer_size(int ssize, int max_sector, int max_size)
{
	SUPBOUND(max_sector, fsector_t + max_size);

	/* alignment */
	max_sector -= (max_sector % _floppy->sect) % ssize;

	/* transfer size, beginning not aligned */
	current_count_sectors = max_sector - fsector_t;

	return max_sector;
}

static int transfer_size(int ssize, int max_sector, int max_size)
{
	SUPBOUND(max_sector, fsector_t + max_size);

	/* alignment */
	max_sector -= (max_sector % _floppy->sect) % ssize;

	/* transfer size, beginning not aligned */
	current_count_sectors = max_sector - fsector_t;

	return max_sector;
}
