PCI: pciehp: Don't disable the link permanently during removal

We need future link up events for hot-add, thus don't disable the link
permanently during device removal. Also, remove the static functions that
are now left unused.

This reverts part of 2debd928

 ("PCI: pciehp: Disable/enable link during
slot power off/on").  This was discussed at the URL below, where it was
revealed that it was done for a bug in a PCIe repeater chip on that
particular platform.

Link: https://lkml.kernel.org/r/CAErSpo72KZ-a2OSQLWoK71GCgwBt676XZdGt4tEYm-6UYnLmPw@mail.gmail.com
Signed-off-by: Rajat Jain <rajatxjain@gmail.com>
Signed-off-by: Rajat Jain <rajatjain@juniper.net>
Signed-off-by: Guenter Roeck <groeck@juniper.net>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>