pinctrl: add one more "const" for generic function groups

Generic code doesn't modify those strings and .get_function_groups
callback has that extra "const" as well. This allows more flexibility in
GENERIC_PINMUX_FUNCTIONS users.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20211216162206.8027-4-zajec5@gmail.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinmux.c

@@ -875,7 +875,7 @@ EXPORT_SYMBOL_GPL(pinmux_generic_get_function);
  */
 int pinmux_generic_add_function(struct pinctrl_dev *pctldev,
 				const char *name,
-				const char **groups,
+				const char * const *groups,
 				const unsigned int num_groups,
 				void *data)
 {

drivers/pinctrl/pinmux.h

@@ -129,7 +129,7 @@ static inline void pinmux_init_device_debugfs(struct dentry *devroot,
  */
 struct function_desc {
 	const char *name;
-	const char **group_names;
+	const char * const *group_names;
 	int num_group_names;
 	void *data;
 };
@@ -150,7 +150,7 @@ struct function_desc *pinmux_generic_get_function(struct pinctrl_dev *pctldev,
 
 int pinmux_generic_add_function(struct pinctrl_dev *pctldev,
 				const char *name,
-				const char **groups,
+				const char * const *groups,
 				unsigned const num_groups,
 				void *data);