PCI/AER: Replace struct pcie_device with pci_dev

The AER driver only needed the pcie_device to get to the port pci_dev.
Save the pci_dev pointer directly in struct aer_rpc and remove the
unnecessary indirection.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>