arm64: dts: allwinner: a64: bananapi-m64: Add LED device node

The Bananapi-M64 has 3 LEDS in red, green, and blue. These are toggled
via GPIO lines, which drive transistors that control current across the
LEDS. The red LED is by default on, via an additional pull-up on the
control line. We consider this means that it is a power indicator.
So we set the "default-on" property for it.

The pingroups the GPIO lines belong to require external regulators be
enabled to be able to drive the GPIO high. These regulators also have
other purposes. However the pin controller does not have bindings for
regulators. Here we just set them to always-on.

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