powerpc: Move cpu_setup_6xx.S and temp.c over to arch/powerpc

Also renamed temp.c to tau_6xx.c (for thermal assist unit) and updated
the Kconfig option description and help text for CONFIG_TAU.

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index e7fddf1..754c227 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -34,7 +34,8 @@
 obj-$(CONFIG_GENERIC_TBSYNC)	+= smp-tbsync.o
 obj64-$(CONFIG_PPC_MULTIPLATFORM) += nvram_64.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
-obj-$(CONFIG_6xx)		+= idle_6xx.o l2cr_6xx.o
+obj-$(CONFIG_6xx)		+= idle_6xx.o l2cr_6xx.o cpu_setup_6xx.o
+obj-$(CONFIG_TAU)		+= tau_6xx.o
 
 ifeq ($(CONFIG_PPC_MERGE),y)