cris/PCI: factor out pcibios_setup()

The PCI core provides a generic pcibios_setup() routine.  Drop this
architecture-specific version in favor of that.

This patch fixes what looks like a bug in cris, which implements
pcibios_setup() such that pci_setup() doesn't look for any generic
options.

Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>