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

include/linux/ide.h

@@ -1295,7 +1295,7 @@ static inline void ide_dump_identify(u8 *id)
 static inline int hwif_to_node(ide_hwif_t *hwif)
 {
 	struct pci_dev *dev = to_pci_dev(hwif->dev);
-	return dev ? pcibus_to_node(dev->bus) : -1;
+	return hwif->dev ? pcibus_to_node(dev->bus) : -1;
 }
 
 static inline ide_drive_t *ide_get_paired_drive(ide_drive_t *drive)