clocksource/drivers/dw_apb_timer: 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/dw_apb_timer_of.c

@@ -143,7 +143,7 @@ static struct delay_timer dw_apb_delay_timer = {
 #endif
 
 static int num_called;
-static void __init dw_apb_timer_init(struct device_node *timer)
+static int __init dw_apb_timer_init(struct device_node *timer)
 {
 	switch (num_called) {
 	case 0:
@@ -164,8 +164,10 @@ static void __init dw_apb_timer_init(struct device_node *timer)
 	}
 
 	num_called++;
+
+	return 0;
 }
-CLOCKSOURCE_OF_DECLARE(pc3x2_timer, "picochip,pc3x2-timer", dw_apb_timer_init);
-CLOCKSOURCE_OF_DECLARE(apb_timer_osc, "snps,dw-apb-timer-osc", dw_apb_timer_init);
-CLOCKSOURCE_OF_DECLARE(apb_timer_sp, "snps,dw-apb-timer-sp", dw_apb_timer_init);
-CLOCKSOURCE_OF_DECLARE(apb_timer, "snps,dw-apb-timer", dw_apb_timer_init);
+CLOCKSOURCE_OF_DECLARE_RET(pc3x2_timer, "picochip,pc3x2-timer", dw_apb_timer_init);
+CLOCKSOURCE_OF_DECLARE_RET(apb_timer_osc, "snps,dw-apb-timer-osc", dw_apb_timer_init);
+CLOCKSOURCE_OF_DECLARE_RET(apb_timer_sp, "snps,dw-apb-timer-sp", dw_apb_timer_init);
+CLOCKSOURCE_OF_DECLARE_RET(apb_timer, "snps,dw-apb-timer", dw_apb_timer_init);