media: i2c/adp1653: set enable gpio to output

Without setting the direction of a gpio to output a call to
gpiod_set_value doesn't have a defined outcome.

Furthermore this is one caller less that stops us making the flags
argument to gpiod_get*() mandatory.

Acked-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>