powerpc: clean up after powermac build merge

Complete moving arch/ppc64/kernel/mpic.h,
        include/asm-ppc/reg.h, include/asm-ppc64/kdebug.h
	        and include/asm-ppc64/kprobes.h
Add arch/powerpc/platforms/Makefile and use it from
	arch/powerpc/Makefile
Introduce OLDARCH temporarily so we can point back to
	the originating architecture

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
diff --git a/arch/ppc64/kernel/rtas_pci.c b/arch/ppc64/kernel/rtas_pci.c
index 4a9719b..4d920dd 100644
--- a/arch/ppc64/kernel/rtas_pci.c
+++ b/arch/ppc64/kernel/rtas_pci.c
@@ -38,8 +38,8 @@
 #include <asm/pci-bridge.h>
 #include <asm/iommu.h>
 #include <asm/rtas.h>
+#include <asm/mpic.h>
 
-#include "mpic.h"
 #include "pci.h"
 
 /* RTAS tokens */