MIPS: PCI: use list_for_each_entry() for bus->devices traversal

Replace open-coded list traversal with list_for_each_entry().

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3200/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>