PCI: Fix reference leak in pci_register_host_bridge()

In the Linux kernel, the following vulnerability has been resolved:

PCI: Fix reference leak in pci_register_host_bridge()

If device_register() fails, call put_device() to give up the reference to

avoid a memory leak, per the comment at device_register().

Found by code review.

[bhelgaas: squash Dan Carpenter's double free fix from

https://lore.kernel.org/r/[email protected]]