gpio: mockup: fix kerneldoc

The pull field of the line state struct is undocumented. Fix it.

Fixes: 2a9e27408e ("gpio: mockup: rework debugfs interface")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-mockup.c

@@ -39,6 +39,8 @@
  * struct gpio_pin_status - structure describing a GPIO status
  * @dir:       Configures direction of gpio as "in" or "out"
  * @value:     Configures status of the gpio as 0(low) or 1(high)
+ * @pull:      Configures the current pull of the GPIO as 0 (pull-down) or
+ *             1 (pull-up)
  */
 struct gpio_mockup_line_status {
 	int dir;