gpio: madera: Add missing const

madera_gpio_chip is only used as a template so it can be marked as const.

Signed-off-by: Charles Keepax <[e-mail]>
Signed-off-by: Bartosz Golaszewski <[e-mail]>

drivers/gpio/gpio-madera.c

···
 			 MADERA_GPIO1_CTRL_1 + reg_offset, ret);
 }
 
-static struct gpio_chip madera_gpio_chip = {
+static const struct gpio_chip madera_gpio_chip = {
 	.label			= "madera",
 	.owner			= THIS_MODULE,
 	.request		= gpiochip_generic_request,