Prevent IDE boot ops on NUMA system

Without this patch a Opteron test system here oopses at boot with
current git.

Calling to_pci_dev() on a NULL pointer gives a negative value so the
following NULL pointer check never triggers and then an illegal address
is referenced.  Check the unadjusted original device pointer for NULL
instead.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>