PCI: Move pci_proc_attach_device() to pci_bus_add_device()

4f535093 ("PCI: Put pci_dev in device tree as early as possible")
moved pci_proc_attach_device() from pci_bus_add_device() to
pci_device_add().

This moves it back to pci_bus_add_device(), essentially reverting that
part of 4f535093

.  This makes it symmetric with pci_stop_dev(),
where we call pci_proc_detach_device() and pci_remove_sysfs_dev_files()
and set dev->is_added = 0.

[bhelgaas: changelog, create sysfs then attach proc for symmetry]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>