pinctrl: sunxi: Add Allwinner A13 pin functions

The initial driver contained only a limited set of pins functions
because we lacked of documentation on it.

Now that we have such documentation, finish to fill the array.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>