[POWERPC] Conditionally compile e200 and e500 platforms in cputable

The e200 and e500 platforms are separated in various parts of the kernel with
ifdefs, most notably reg_booke.h and traps.c.  The new machine_check rework
requires them to be similarly separated in cputable.c to avoid compile errors.

Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>