gpio:gpiolib: use static const char const * for a suffixes array

Checkpatch complains, and probably with good reason that we should use
const char const * for the static constant array that never gets
changed.
Signed-off-by: NOlliver Schinagl <oliver@schinagl.nl>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -1657,7 +1657,7 @@ static struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
 				      unsigned int idx,
 				      enum gpio_lookup_flags *flags)
 {
-	static const char *suffixes[] = { "gpios", "gpio" };
+	static const char const *suffixes[] = { "gpios", "gpio" };
 	char prop_name[32]; /* 32 is max size of property name */
 	enum of_gpio_flags of_flags;
 	struct gpio_desc *desc;