regulator: gpio-regulator: Staticize of_get_gpio_regulator_config()

of_get_gpio_regulator_config() is only used in gpio-regulator.c, make it static.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/regulator/gpio-regulator.c b/drivers/regulator/gpio-regulator.c
index d819ba7..9d39eb4 100644
--- a/drivers/regulator/gpio-regulator.c
+++ b/drivers/regulator/gpio-regulator.c
@@ -132,7 +132,7 @@
 	.list_voltage = gpio_regulator_list_voltage,
 };
 
-struct gpio_regulator_config *
+static struct gpio_regulator_config *
 of_get_gpio_regulator_config(struct device *dev, struct device_node *np)
 {
 	struct gpio_regulator_config *config;