i5400_edac: Avoid calling pci_put_device() twice

When i5400_edac driver is removed and re-loaded a few times, it causes
an OOPS, as it is currently decrementing some PCI device usage two
times.

When called inside a loop, pci_get_device() will call
pci_put_device(). That mangles the error count. In this specific
case, it seems easier to just duplicate the call.

Also fixes the error logic when pci_get_device fails.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>