leds: leds-gpio-register: Supply description for param 'id'

Fixes the following W=1 kernel build warning(s):

 drivers/leds/leds-gpio-register.c:24: warning: Function parameter or member 'id' not described in 'gpio_led_register_device'

Cc: Pavel Machek <pavel@ucw.cz>
Cc: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
Cc: linux-leds@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

drivers/leds/leds-gpio-register.c

@@ -11,6 +11,7 @@
 /**
  * gpio_led_register_device - register a gpio-led device
  * @pdata: the platform data used for the new device
+ * @id: platform ID
  *
  * Makes a copy of pdata and pdata->leds and registers a new leds-gpio device
  * with the result. This allows to have pdata and pdata-leds in .init.rodata