gpiolib: Add GPIOCHIP_NAME definition

The string literal "gpiochip" is used in several places.
Add a definition for it, and use it everywhere, to make sure everything
stays in sync.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20191127084253.16356-2-geert+renesas@glider.be
Reviewed-by: Ulrich Hecht <uli+renesas@fpond.eu>
Reviewed-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index fbf6b1a..23e3d33 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -762,10 +762,9 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
 		parent = &gdev->dev;
 
 	/* use chip->base for the ID; it's already known to be unique */
-	dev = device_create_with_groups(&gpio_class, parent,
-					MKDEV(0, 0),
-					chip, gpiochip_groups,
-					"gpiochip%d", chip->base);
+	dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip,
+					gpiochip_groups, GPIOCHIP_NAME "%d",
+					chip->base);
 	if (IS_ERR(dev))
 		return PTR_ERR(dev);