PCI: remove pcibios_fixup_ghosts()

This function was obviously never being used since early 2.5 days as any
device that it would try to remove would never really be removed from
the system due to the PCI device list being held in the driver core, not
the general list of PCI devices.

As we have not had a single report of a problem here in 4 years, I think
it's safe to remove now.

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