PCI/portdrv: Remove unused pcie_port_acpi_setup()

02bfeb48 ("PCI/portdrv: Simplify PCIe feature permission checking")
removed the only call of pcie_port_acpi_setup() and removed portdrv_acpi.o
from the Makefile, but I forgot to remove pcie_port_acpi_setup() itself.

Remove pcie_port_acpi_setup() and the drivers/pci/pcie/portdrv_acpi.c file.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>