In case the gpiochip doesn't have the .dev field set, as is the case
in here, it is not possible to reference this device in DT as a GPIO
controller. A good example of this problem is that gpio-leds can not
be used when connected to this chip, the gpio-leds driver bails out
with -EPROBE_DEFER.

Fix this problem by setting the .dev field of the gpio_chip to the
parent i2c device.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Mans Rullgard <mans@mansr.com>
Cc: Olaf Mandel <o.mandel@menlosystems.com>
Cc: Semen Protsenko <semen.protsenko@globallogic.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>