[media] : cxd2830r: use gpiochip data pointer

This makes the driver use the data pointer added to the gpio_chip
to store a pointer to the state container instead of relying on
container_of().

Cc: Antti Palosaari <crope@iki.fi>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>