pinctrl-sunxi: Fix sun5i-a13 port F multiplexing

The correct value for selecting the mmc0 function on port F pins is 2 not 4,
as per the data-sheet:
http://dl.linux-sunxi.org/A13/A13%20Datasheet%20-%20v1.12%20%282012-03-29%29.pdf



Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>