leds: aat1290: pass flags parameter to devm_gpiod_get

Since 39b2bbe3

 (gpio: add flags argument to gpiod_get*() functions)
which appeared in v3.17-rc1, the gpiod_get* functions take an additional
parameter that allows to specify direction and initial value for output.

In this case the driver cannot easily be simplified but as the flags
parameter will become mandatory soon this change is necessary
beforehand.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>