i82875p_edac: Assign PCI resources before adding device

Assign PCI resources before pci_bus_add_device().  The resources must be
assigned before a driver can claim the device.

[bhelgaas: changelog]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>