gpio: nomadik: make clock optional

Not all platforms using this platform driver expose a clock for this
GPIO controller. Turn devm_clk_get() into devm_clk_get_optional() to
avoid failing when no clocks are provided.
Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Link: https://lore.kernel.org/r/20240228-mbly-gpio-v2-20-3ba757474006@bootlin.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-nomadik.c

@@ -531,7 +531,7 @@ struct nmk_gpio_chip *nmk_gpio_populate_chip(struct device_node *np,
 	}
 	nmk_chip->addr = base;
 
-	clk = devm_clk_get(gpio_dev, NULL);
+	clk = devm_clk_get_optional(gpio_dev, NULL);
 	if (IS_ERR(clk)) {
 		platform_device_put(gpio_pdev);
 		return (void *)clk;