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 inline void fallback_on_nodma_alloc(char **addr, size_t l)
{
#ifdef FLOPPY_CAN_FALLBACK_ON_NODMA
	if (*addr)
		return;		/* we have the memory */
	if (can_use_virtual_dma != 2)
		return;		/* no fallback allowed */
	pr_info("DMA memory shortage. Temporarily falling back on virtual DMA\n");
	*addr = (char *)nodma_mem_alloc(l);
#else
	return;
#endif
}

static inline void fallback_on_nodma_alloc(char **addr, size_t l)
{
#ifdef FLOPPY_CAN_FALLBACK_ON_NODMA
	if (*addr)
		return;		/* we have the memory */
	if (can_use_virtual_dma != 2)
		return;		/* no fallback allowed */
	pr_info("DMA memory shortage. Temporarily falling back on virtual DMA\n");
	*addr = (char *)nodma_mem_alloc(l);
#else
	return;
#endif
}
