MIPS: PCI: Netlogic XLP9XX support

Add PCI support for Netlogic XLP9XX. The PCI registers and
SoC bus numbers have changed in XLP9XX.

Also skip a few (bus,dev,fn) combinations which have issues when
read.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6284/