gpio: Pass a flag to gpiochip_request_own_desc()

Before things go out of hand, make it possible to pass
flags when requesting "own" descriptors from a gpio_chip.
This is necessary if the chip wants to request a GPIO with
active low semantics, for example.

Cc: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Roger Quadros <rogerq@ti.com>
Reviewed-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/driver-api/gpio/driver.rst

@@ -434,7 +434,9 @@ try_module_get()). A GPIO driver can use the following functions instead
 to request and free descriptors without being pinned to the kernel forever::
 
 	struct gpio_desc *gpiochip_request_own_desc(struct gpio_desc *desc,
-						    const char *label)
+						    u16 hwnum,
+						    const char *label,
+						    enum gpiod_flags flags)
 
 	void gpiochip_free_own_desc(struct gpio_desc *desc)