[S390] merge cpu.h into cputime.h

All definition in cpu.h have to do with cputime accounting. Move
them to cputime.h and remove the header file.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/s390_ext.c b/arch/s390/kernel/s390_ext.c
index a0d2d55..6b0686d 100644
--- a/arch/s390/kernel/s390_ext.c
+++ b/arch/s390/kernel/s390_ext.c
@@ -13,7 +13,7 @@
 #include <linux/errno.h>
 #include <linux/kernel_stat.h>
 #include <linux/interrupt.h>
-#include <asm/cpu.h>
+#include <asm/cputime.h>
 #include <asm/lowcore.h>
 #include <asm/s390_ext.h>
 #include <asm/irq_regs.h>