MIPS: pci-legacy: use generic pci_enable_resources

Follow the reasoning from commit 842de40d ("PCI: add generic
pci_enable_resources()"):

  The only functional difference from the MIPS version is that the
  generic one uses "!r->parent" to check for resource collisions
  instead of "!r->start && r->end".

That should have no effect on any pci-legacy driver.

Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>