gpiolib: define gpio suffixes globally

Avoid multiple identical definitions of the gpio suffix strings by putting
them into a global constant array.

Signed-off-by: Rojhalat Ibrahim <imr@rtschenk.de>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index cadba26..205dd12 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -27,6 +27,9 @@
 	bool active_low;
 };
 
+/* gpio suffixes used for ACPI and device tree lookup */
+static const char * const gpio_suffixes[] = { "gpios", "gpio" };
+
 #ifdef CONFIG_ACPI
 void acpi_gpiochip_add(struct gpio_chip *chip);
 void acpi_gpiochip_remove(struct gpio_chip *chip);