pinctrl: madera: Fix possible NULL pointer with pdata config

If we are being configured via pdata we don't necessarily have
any gpio mappings being configured that way so pdata->gpio_config
could be NULL.
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/cirrus/pinctrl-madera-core.c

@@ -1040,7 +1040,7 @@ static int madera_pin_probe(struct platform_device *pdev)
 	}
 
 	/* if the configuration is provided through pdata, apply it */
-	if (pdata) {
+	if (pdata && pdata->gpio_configs) {
 		ret = pinctrl_register_mappings(pdata->gpio_configs,
 						pdata->n_gpio_configs);
 		if (ret) {