pinctrl: remove extern specifier for functions in machine.h

Extern is the default specifier for a function, no need to define it.

Suggested-by: Andy Shevchenko <andy@kernel.org>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
Link: https://lore.kernel.org/20250520-aaeon-up-board-pinctrl-support-v6-2-dcb3756be3c6@bootlin.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Author: thom24

include/linux/pinctrl/machine.h

@@ -153,10 +153,10 @@ struct pinctrl_map;
 
 #ifdef CONFIG_PINCTRL
 
-extern int pinctrl_register_mappings(const struct pinctrl_map *map,
-				     unsigned int num_maps);
-extern void pinctrl_unregister_mappings(const struct pinctrl_map *map);
-extern void pinctrl_provide_dummies(void);
+int pinctrl_register_mappings(const struct pinctrl_map *map,
+			      unsigned int num_maps);
+void pinctrl_unregister_mappings(const struct pinctrl_map *map);
+void pinctrl_provide_dummies(void);
 #else
 
 static inline int pinctrl_register_mappings(const struct pinctrl_map *map,