PCI/ASPM: Remove redundant PCIe port type checking

We decide in alloc_pcie_link_state() whether to allocate a pcie_link_state
for a device.  After that, it's sufficient to check pdev->link_state.  We
don't need to check the PCIe port type again.

Remove the redundant PCIe port type checking.

[bhelgaas: changelog]
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>