In order to start migrating away from accessing struct gpio_chip by
users other than their owners, let's first make the reference management
functions for the opaque struct gpio_device public in the driver.h
header.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>