PCI/portdrv: Remove unused pcie_port_bus_{,un}register() declarations

Commit c6c889d9 ("PCI/portdrv: Remove pcie_port_bus_type link order
dependency") removed pcie_port_bus_{,un}register() but erroneously
retained their declarations in portdrv.h.  Remove them as well.

Link: https://lore.kernel.org/r/7fd76b0591c37287ab94d911d8fd9ab9a2afcd16.1627638184.git.lukas@wunner.deSigned-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

drivers/pci/pcie/portdrv.h

@@ -118,8 +118,6 @@ int pcie_port_device_runtime_suspend(struct device *dev);
 int pcie_port_device_runtime_resume(struct device *dev);
 #endif
 void pcie_port_device_remove(struct pci_dev *dev);
-int __must_check pcie_port_bus_register(void);
-void pcie_port_bus_unregister(void);
 
 struct pci_dev;