PCI: Remove pcibios_add_platform_entries()

Remove pcibios_add_platform_entries().  Architecture-specific attributes
can be achieved by setting pdev->dev.groups.

Link: https://lkml.kernel.org/r/alpine.LFD.2.11.1404141101500.1529@denkbrett


Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>