rtc: brcmstb-waketimer: fix error handling in brcmstb_waketmr_probe()

brcmstb_waketmr_probe() does not disable timer->clk on error paths.

Found by Linux Driver Verification project (linuxtesting.org).

Fixes: c4f07ece ("rtc: brcmstb-waketimer: Add Broadcom STB wake-timer")
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-brcmstb-waketimer.c

@@ -253,7 +253,7 @@ static int brcmstb_waketmr_probe(struct platform_device *pdev)
 	ret = devm_request_irq(dev, timer->irq, brcmstb_waketmr_irq, 0,
 			       "brcmstb-waketimer", timer);
 	if (ret < 0)
-		return ret;
+		goto err_clk;
 
 	timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
 	register_reboot_notifier(&timer->reboot_notifier);
@@ -262,12 +262,21 @@ static int brcmstb_waketmr_probe(struct platform_device *pdev)
 					 &brcmstb_waketmr_ops, THIS_MODULE);
 	if (IS_ERR(timer->rtc)) {
 		dev_err(dev, "unable to register device\n");
-		unregister_reboot_notifier(&timer->reboot_notifier);
-		return PTR_ERR(timer->rtc);
+		ret = PTR_ERR(timer->rtc);
+		goto err_notifier;
 	}
 
 	dev_info(dev, "registered, with irq %d\n", timer->irq);
 
+	return 0;
+
+err_notifier:
+	unregister_reboot_notifier(&timer->reboot_notifier);
+
+err_clk:
+	if (timer->clk)
+		clk_disable_unprepare(timer->clk);
+
 	return ret;
 }