gpiolib: make gpio_device_get() and gpio_device_put() public

gpiolib: make gpio_device_get() and gpio_device_put() public

[ Upstream commit 36aa129f221c9070afd8dff03154ab49702a5b1b ]

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>
Stable-dep-of: 48e1b4d369cf ("gpiolib: remove the GPIO device from the list when it's unregistered")
Signed-off-by: Sasha Levin <sashal@kernel.org>