PCI/core: Use PCI Express Capability accessors

Use PCI Express Capability access functions to simplify core.

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

diff --cc drivers/pci/pci.c
Simple merge

diff --cc drivers/pci/probe.c
Simple merge

diff --cc drivers/pci/quirks.c
Simple merge