clocksource/drivers/h8300_tpu: 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/h8300_tpu.c

@@ -119,15 +119,16 @@ static struct tpu_priv tpu_priv = {
 #define CH_L 0
 #define CH_H 1
 
-static void __init h8300_tpu_init(struct device_node *node)
+static int __init h8300_tpu_init(struct device_node *node)
 {
 	void __iomem *base[2];
 	struct clk *clk;
+	int ret = -ENXIO;
 
 	clk = of_clk_get(node, 0);
 	if (IS_ERR(clk)) {
 		pr_err("failed to get clock for clocksource\n");
-		return;
+		return PTR_ERR(clk);
 	}
 
 	base[CH_L] = of_iomap(node, CH_L);
@@ -144,14 +145,13 @@ static void __init h8300_tpu_init(struct device_node *node)
 	tpu_priv.mapbase1 = base[CH_L];
 	tpu_priv.mapbase2 = base[CH_H];
 
-	clocksource_register_hz(&tpu_priv.cs, clk_get_rate(clk) / 64);
-
-	return;
+	return clocksource_register_hz(&tpu_priv.cs, clk_get_rate(clk) / 64);
 
 unmap_L:
 	iounmap(base[CH_H]);
 free_clk:
 	clk_put(clk);
+	return ret;
 }
 
-CLOCKSOURCE_OF_DECLARE(h8300_tpu, "renesas,tpu", h8300_tpu_init);
+CLOCKSOURCE_OF_DECLARE_RET(h8300_tpu, "renesas,tpu", h8300_tpu_init);