hang w/ppc6xx_defconfig related to 'simple-bus' compatible

[Kumar Gala]

I'm trying to get the ppc6xx_defconfig booting on any 8641 (74xx/e600)  
system.  If I remove the 'simple-bus' compatible from the soc node in  
the .dts it works.  Otherwise it hangs at but and looks to be crashed  
in the serial driver due to accessing memory at 0.

I've tried the same .dts (w/'simple-bus') using the  
mpc8641_hpcn_defconfig and things work.

Any one got any ideas?

- k