s390/vtime: Use get_cpu_timer()

Instead of implementing get_vtimer() use get_cpu_timer()
which does the same.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

arch/s390/kernel/vtime.c

@@ -33,14 +33,6 @@ static DEFINE_PER_CPU(u64, mt_scaling_mult) = { 1 };
 static DEFINE_PER_CPU(u64, mt_scaling_div) = { 1 };
 static DEFINE_PER_CPU(u64, mt_scaling_jiffies);
 
-static inline u64 get_vtimer(void)
-{
-	u64 timer;
-
-	asm volatile("stpt %0" : "=Q" (timer));
-	return timer;
-}
-
 static inline void set_vtimer(u64 expires)
 {
 	u64 timer;
@@ -223,7 +215,7 @@ static u64 vtime_delta(void)
 {
 	u64 timer = S390_lowcore.last_update_timer;
 
-	S390_lowcore.last_update_timer = get_vtimer();
+	S390_lowcore.last_update_timer = get_cpu_timer();
 
 	return timer - S390_lowcore.last_update_timer;
 }