gpio: pxa: Avoid a warning when gpio0 and gpio1 IRQS are not there

Not all platforms use those. Let's use
platform_get_irq_byname_optional() instead platform_get_irq_byname() so
that we avoid a useless warning:

  [    1.359455] pxa-gpio d4019000.gpio: IRQ gpio0 not found
  [    1.359583] pxa-gpio d4019000.gpio: IRQ gpio1 not found
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

drivers/gpio/gpio-pxa.c

@@ -652,8 +652,8 @@ static int pxa_gpio_probe(struct platform_device *pdev)
 	if (!pchip->irqdomain)
 		return -ENOMEM;
 
-	irq0 = platform_get_irq_byname(pdev, "gpio0");
-	irq1 = platform_get_irq_byname(pdev, "gpio1");
+	irq0 = platform_get_irq_byname_optional(pdev, "gpio0");
+	irq1 = platform_get_irq_byname_optional(pdev, "gpio1");
 	irq_mux = platform_get_irq_byname(pdev, "gpio_mux");
 	if ((irq0 > 0 && irq1 <= 0) || (irq0 <= 0 && irq1 > 0)
 		|| (irq_mux <= 0))