[S390] hibernation: remove dead file

There is no caller of do_after_copyback() anywhere. Remove it.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/power/Makefile

@@ -4,5 +4,4 @@
 
 obj-$(CONFIG_HIBERNATION) += suspend.o
 obj-$(CONFIG_HIBERNATION) += swsusp.o
-obj-$(CONFIG_HIBERNATION) += swsusp_64.o
 obj-$(CONFIG_HIBERNATION) += swsusp_asm64.o

arch/s390/power/swsusp_64.c

-/*
- * Support for suspend and resume on s390
- *
- * Copyright IBM Corp. 2009
- *
- * Author(s): Hans-Joachim Picht <hans@linux.vnet.ibm.com>
- *
- */
-
-#include <asm/system.h>
-#include <linux/interrupt.h>
-
-void do_after_copyback(void)
-{
-	mb();
-}
-