PCIe: portdrv: call pci_disable_device during remove

The PCIe port driver calls pci_enable_device() during probe but
never calls pci_disable_device() during remove.

Cc: stable@kernel.org
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>