clocksource/drivers/timer-of: Add timer_of_exit function

The timer-of API does not provide a function to undo what has been done by
the timer_of_init() function.

Add a timer_of_exit() function.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
diff --git a/drivers/clocksource/timer-of.c b/drivers/clocksource/timer-of.c
index c79122d..7c64a5c1 100644
--- a/drivers/clocksource/timer-of.c
+++ b/drivers/clocksource/timer-of.c
@@ -176,3 +176,15 @@ int __init timer_of_init(struct device_node *np, struct timer_of *to)
 		timer_base_exit(&to->of_base);
 	return ret;
 }
+
+void timer_of_exit(struct timer_of *to)
+{
+	if (to->flags & TIMER_OF_IRQ)
+		timer_irq_exit(&to->of_irq);
+
+	if (to->flags & TIMER_OF_CLOCK)
+		timer_clk_exit(&to->of_clk);
+
+	if (to->flags & TIMER_OF_BASE)
+		timer_base_exit(&to->of_base);
+}