We don't need anything arch-specific in pcibios_enable_device(), so drop
the arch implementation and use the default generic one.

Note: pci_enable_resources() checks that r->parent is non-NULL, which
basically checks that pci_claim_resource() or request_resource() has been
called for each BAR.  I don't see where that happens for tile, but this
patch doesn't change that behavior, so if it worked before, it should still
work.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>