x86: unify power/cpu_(32|64).c

This is the last unification step. Here we do remove one of the files
and rename the left one as cpu.c, as both are now the same.
Also update power/Makefile, telling it to build cpu.o, instead of
cpu_(32|64).o

Signed-off-by: Sergio Luis <sergio@larces.uece.br>
Signed-off-by: Lauro Salmito <laurosalmito@gmail.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/arch/x86/power/Makefile b/arch/x86/power/Makefile
index 58b32db..de2abbd 100644
--- a/arch/x86/power/Makefile
+++ b/arch/x86/power/Makefile
@@ -3,5 +3,5 @@
 nostackp := $(call cc-option, -fno-stack-protector)
 CFLAGS_cpu_$(BITS).o	:= $(nostackp)
 
-obj-$(CONFIG_PM_SLEEP)		+= cpu_$(BITS).o
+obj-$(CONFIG_PM_SLEEP)		+= cpu.o
 obj-$(CONFIG_HIBERNATION)	+= hibernate_$(BITS).o hibernate_asm_$(BITS).o