[POWERPC] EEH: balance pcidev_get/put calls

This corrects a pci_dev get/put imbalance that can occur only in
highly unlikely situations (kmalloc failures, pci devices with
overlapping resource addresses).  No actual failures seen, this was
spotted during code review.

Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>