[POWERPC] 85xx: Add quirk to ignore bogus FPGA on CDS

The newer Arcadia boards for CDS have an FPGA that shows up on PCI
however isn't a real PCI device.  Add a quirk to just ignore the
FPGA.

This is based on the following patch from Andy & York:

http://ozlabs.org/pipermail/linuxppc-dev/2007-February/032042.html

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>