PCI/ACPI: Remove support of ACPI PCI subdrivers

Both sub-drivers of the "PCI Root Bridge ("pci_bridge")" driver, "acpiphp"
and "pci_slot", have been converted to hook directly into the PCI core.

With the conversions there are no remaining usages of the 'struct
acpi_pci_driver' list based infrastructure.  This patch removes it.

Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Yinghai Lu <yinghai@kernel.org>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Toshi Kani <toshi.kani@hp.com>