Little-endian PowerPC

Also, the IXP425 has a proprietary firmware that runs on the microengines that drive the networking subsystem. These always run big-endian, so it makes sense to have the whole chip be big endian (the microengines are not byte-swappable like the ARM core is.)

I did a lot of coding for the IXP2855, which is the IXP425's discontinued big brother.