PCI: Remove unused field pcie_type from struct pci_dev

With introduction of pci_pcie_type(), pci_dev->pcie_type field becomes
redundant, so remove it.

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>