gpio: Fix build warnings on undefined struct pinctrl_dev

This fixes the warnings:

* include/linux/gpio.h:254:11: warning: 'struct pinctrl_dev' declared
  inside parameter list will not be visible outside of this definition
  or declaration
* include/linux/gpio/driver.h:602:11: warning: 'struct pinctrl_dev'
  declared inside parameter list will not be visible outside of this
  definition or declaration

Fixes: 78b99577b393 ("pinctrl: remove unused pin_is_valid()")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Enrico Weigelt <info@metux.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/gpio.h b/include/linux/gpio.h
index 39745b8bdd65..40915b461f18 100644
--- a/include/linux/gpio.h
+++ b/include/linux/gpio.h
@@ -106,6 +106,7 @@ void devm_gpio_free(struct device *dev, unsigned int gpio);
 
 struct device;
 struct gpio_chip;
+struct pinctrl_dev;
 
 static inline bool gpio_is_valid(int number)
 {