clocksource/drivers/dw_apb_timers_of: Fix IO endianness causing time jumps

The dw_apb_timer_of timer is using __raw_readl() to access the
timer register, which is causing issues when the system is
running in big endian mode. Fix this by using readl_relaxed()
which should account for the endian settings.

This fixes issues where the time jumps around in the dmesg
output due to returnling __le32 values.

For an example, these two console lines show time running
backwards:

[   49.882572] CPU1: failed to come online
[   43.282457] Brought up 1 CPUs

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Linux ARM Kernel <linux-arm-kernel@lists.infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: digetx@gmail.com
Cc: hdegoede@redhat.com
Cc: laurent.pinchart+renesas@ideasonboard.com
Cc: maxime.ripard@free-electrons.com
Cc: viresh.kumar@linaro.org
Link: http://lkml.kernel.org/r/1427746633-9137-10-git-send-email-daniel.lezcano@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

drivers/clocksource/dw_apb_timer_of.c

@@ -108,7 +108,7 @@ static void __init add_clocksource(struct device_node *source_timer)
 
 static u64 notrace read_sched_clock(void)
 {
-	return ~__raw_readl(sched_io_base);
+	return ~readl_relaxed(sched_io_base);
 }
 
 static const struct of_device_id sptimer_ids[] __initconst = {