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

 drivers/leds/leds-is31fl32xx.c:85: warning: Function parameter or member 'sw_shutdown_func' not described in 'is31fl32xx_chipdef'

Cc: Pavel Machek <pavel@ucw.cz>
Cc: David Rivshin <drivshin@allworx.com>
Cc: linux-leds@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>