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

 drivers/leds/leds-as3645a.c:198: warning: expecting prototype for as3645a_set_config(). Prototype was for as3645a_set_current() instead

Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: linux-leds@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>