powerpc: Rename files to have consistent _32/_64 suffixes

This doesn't change any code, just renames things so we consistently
have foo_32.c and foo_64.c where we have separate 32- and 64-bit
versions.

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index eb1224c..0648640 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -112,7 +112,7 @@
 # Default to the common case.
 KBUILD_DEFCONFIG := common_defconfig
 
-head-y				:= arch/powerpc/kernel/head.o
+head-y				:= arch/powerpc/kernel/head_32.o
 head-$(CONFIG_PPC64)		:= arch/powerpc/kernel/head_64.o
 head-$(CONFIG_8xx)		:= arch/powerpc/kernel/head_8xx.o
 head-$(CONFIG_4xx)		:= arch/powerpc/kernel/head_4xx.o