PCI: fix __must_check warnings

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 3ec7255..c9bb7be 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -431,7 +431,7 @@
 struct pci_dev * pci_scan_single_device(struct pci_bus *bus, int devfn);
 void pci_device_add(struct pci_dev *dev, struct pci_bus *bus);
 unsigned int pci_scan_child_bus(struct pci_bus *bus);
-void pci_bus_add_device(struct pci_dev *dev);
+int __must_check pci_bus_add_device(struct pci_dev *dev);
 void pci_read_bridge_bases(struct pci_bus *child);
 struct resource *pci_find_parent_resource(const struct pci_dev *dev, struct resource *res);
 int pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge);