[POWERPC] Remove APUS support from arch/ppc

Current status of APUS:
- arch/powerpc/: removed in 2.6.23
- arch/ppc/: marked BROKEN since 2 years

This therefore removes the remaining parts of APUS support from
arch/ppc, include/asm-ppc, arch/powerpc and include/asm-powerpc.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>