MIPS: Octeon: Add support for OCTEON II PCIe

OCTEON II SOCs have a different PCIe implementation than is present in
OCTEON Plus.

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2985/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>