ARM: dts: sun4i: Remove underscores from nodes names

Some GPIO pinctrl nodes cannot be easily removed, because they would also
change the pin configuration, for example to add a pull resistor or change
the current delivered by the pin.

Those nodes still have underscores and unit-addresses in their node names
in our DTs, so adjust their name to remove the warnings. Use that occasion
to also fix some poorly chosen node-names.

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