[PATCH] powerpc: Updated Kconfig and Makefiles for 83xx support

Updated Kconfig & Makefiles in prep for adding support for the Freescale
MPC83xx family of processors to arch/powerpc.  Moved around some config
options that are more globally applicable to other PowerPC processors.
Added a temporary config option (83xx) to match existing arch/ppc support
for the MPC83xx line.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>