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>