PCI: hotplug/cpcihp, fix pci device refcounting

Stanse found an ommitted pci_dev_put on one error path in
cpcihp_generic_init. The path is taken on !dev, but also when
dev->hdr_type != PCI_HEADER_TYPE_BRIDGE. However it omits to
pci_dev_put on the latter.

As it is fine to pass NULL to pci_dev_put, put it in there
uncoditionally.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Scott Murray <scott@spiteful.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/hotplug/cpcihp_generic.c

@@ -162,6 +162,7 @@ static int __init cpcihp_generic_init(void)
 	dev = pci_get_slot(bus, PCI_DEVFN(bridge_slot, 0));
 	if(!dev || dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) {
 		err("Invalid bridge device %s", bridge);
+		pci_dev_put(dev);
 		return -EINVAL;
 	}
 	bus = dev->subordinate;