ARM: sunxi: Remove useless allwinner,drive property

The allwinner,drive property set to 10mA was really considered as our
default. Remove all those properties entirely to make that obvious.

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