clocksource: dw_apb_timer_of: Do not trace read_sched_clock

We do not need to trace read_sched_clock function,
so add notrace attribute for this function.
Signed-off-by: Yang Wei <Wei.Yang@windriver.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/dw_apb_timer_of.c

@@ -106,7 +106,7 @@ static void __init add_clocksource(struct device_node *source_timer)
 	sched_rate = rate;
 }
 
-static u64 read_sched_clock(void)
+static u64 notrace read_sched_clock(void)
 {
 	return ~__raw_readl(sched_io_base);
 }