ARM: dts: sunxi: Remove useless pinctrl nodes

We have for the H3 boards some kind of cargo cult apparently, where we
would have a pinctrl node even for GPIOs without any particular settings.

This is pretty much useless, so let's remove them.

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