thermal/drivers/brcmstb_thermal: Interrupt is optional

Utilize platform_get_irq_optional() to silence these messages:

brcmstb_thermal a581500.thermal: IRQ index 0 not found
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20220301181412.2008044-1-f.fainelli@gmail.comSigned-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/thermal/broadcom/brcmstb_thermal.c

@@ -351,7 +351,7 @@ static int brcmstb_thermal_probe(struct platform_device *pdev)
 
 	priv->thermal = thermal;
 
-	irq = platform_get_irq(pdev, 0);
+	irq = platform_get_irq_optional(pdev, 0);
 	if (irq >= 0) {
 		ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
 						brcmstb_tmon_irq_thread,