ARM: dts: sunxi: Fix the LED node names

According to the LED bindings, the LED node names are supposed to be led
plus an optional suffix. Let's fix our users to use that new scheme.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Jernej Skrabec <jernej.skrabec@siol.net>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Link: https://lore.kernel.org/r/20210114113538.1233933-6-maxime@cerno.tech