gpio: dln2: Fix gpio output value in dln2_gpio_direction_output()

dln2_gpio_direction_output() ignored the state passed into it. Fix it.
Also make dln2_gpio_pin_set_out_val return int, so we can check the error value.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Tested-by: Daniel Baluta <daniel.baluta@intel.com>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Octavian Purdila <octavian.purdila@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>