pinctrl: sunxi: Remove gpio_out function from sun5i-a13 PG0/1/2 pins

The A13 user manual states pins PG0/1/2 only have GPIO input and
interrupt functions. Remove the gpio_out functions for these pins.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>