pinctrl: Declare operation structures as const

The pinconf, pinctrl and pinmux operation structures hold function
pointers that are never modified. Declare them as const.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/pinctrl/pinctrl-falcon.c b/drivers/pinctrl/pinctrl-falcon.c
index af97a1f..f9b2a1d 100644
--- a/drivers/pinctrl/pinctrl-falcon.c
+++ b/drivers/pinctrl/pinctrl-falcon.c
@@ -353,7 +353,7 @@
 {
 }
 
-static struct pinconf_ops falcon_pinconf_ops = {
+static const struct pinconf_ops falcon_pinconf_ops = {
 	.pin_config_get			= falcon_pinconf_get,
 	.pin_config_set			= falcon_pinconf_set,
 	.pin_config_group_get		= falcon_pinconf_group_get,