ppc64: default build as the merged 'powerpc' architecture

After the last merge of the new unified 'powerpc' architecture, ppc64 no
longer compiles cleanly as a standalone architecture.  Some bits and
pieces still exist as files under the old ppc64 hierarchy, but the old
"ARCH=ppc64" is dead.

So if "uname" says ppc64, that now implies that the default architecture
should be "powerpc".

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Makefile

@@ -168,7 +168,8 @@ KERNELRELEASE=$(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)$(LOCALVERSION)
 
 SUBARCH := $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \
 				  -e s/arm.*/arm/ -e s/sa110/arm/ \
-				  -e s/s390x/s390/ -e s/parisc64/parisc/ )
+				  -e s/s390x/s390/ -e s/parisc64/parisc/ \
+				  -e s/ppc64/powerpc/ )
 
 # Cross compiling and selecting different set of gcc/bin-utils
 # ---------------------------------------------------------------------------