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