clocksource/drivers/zevio: Convert init function to return error

The init functions do not return any error. They behave as the following:

  - panic, thus leading to a kernel crash while another timer may work and
       make the system boot up correctly

  or

  - print an error and let the caller unaware if the state of the system

Change that by converting the init functions to return an error conforming
to the CLOCKSOURCE_OF_RET prototype.

Proper error handling (rollback, errno value) will be changed later case
by case, thus this change just return back an error or success in the init
function.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/zevio-timer.c

@@ -210,9 +210,9 @@ static int __init zevio_timer_add(struct device_node *node)
 	return ret;
 }
 
-static void __init zevio_timer_init(struct device_node *node)
+static int __init zevio_timer_init(struct device_node *node)
 {
-	BUG_ON(zevio_timer_add(node));
+	return zevio_timer_add(node);
 }
 
-CLOCKSOURCE_OF_DECLARE(zevio_timer, "lsi,zevio-timer", zevio_timer_init);
+CLOCKSOURCE_OF_DECLARE_RET(zevio_timer, "lsi,zevio-timer", zevio_timer_init);