gpio: davinci: Use devm_gpiochip_add_data in place of gpiochip_add_data

Use the devm version of gpiochip_add_data and pass on the
return value. This avoids memory leak due to gpiochip_add_data
in case the driver is unbound.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>