unicore32 time.c: change calculate method for clock_event_device

apply clockevents_calc_mult_shift() to get rid of
shift assignment and mult calculation for osmr0
  -- by advice with Thomas Gleixner

Signed-off-by: Guan Xuetao <gxt@mprc.pku.edu.cn>

arch/unicore32/kernel/time.c

@@ -66,11 +66,6 @@ puv3_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *c)
 static struct clock_event_device ckevt_puv3_osmr0 = {
 	.name		= "osmr0",
 	.features	= CLOCK_EVT_FEAT_ONESHOT,
-#ifdef CONFIG_ARCH_FPGA
-	.shift		= 18, /* correct shift val: 16, but warn_on_slowpath */
-#else
-	.shift          = 30,
-#endif
 	.rating		= 200,
 	.set_next_event	= puv3_osmr0_set_next_event,
 	.set_mode	= puv3_osmr0_set_mode,
@@ -101,8 +96,8 @@ void __init time_init(void)
 	OST_OIER = 0;		/* disable any timer interrupts */
 	OST_OSSR = 0;		/* clear status on all timers */
 
-	ckevt_puv3_osmr0.mult =
-		div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC, ckevt_puv3_osmr0.shift);
+	clockevents_calc_mult_shift(&ckevt_puv3_osmr0, CLOCK_TICK_RATE, 5);
+
 	ckevt_puv3_osmr0.max_delta_ns =
 		clockevent_delta2ns(0x7fffffff, &ckevt_puv3_osmr0);
 	ckevt_puv3_osmr0.min_delta_ns =