dt-bindings: leds: Add Allwinner A100 LED controller

The Allwinner A100, R329, and D1 SoCs contain an LED controller designed
to drive a series of RGB LED pixels. It supports PIO and DMA transfers,
and has configurable timing and pixel format. All three implementations
appear to be identical, so use the oldest as the fallback compatible.

Acked-by: Guo Ren <guoren@kernel.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Tested-by: Trevor Woerner <twoerner@gmail.com>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Link: https://lore.kernel.org/r/20231029212738.7871-2-samuel@sholland.org
Signed-off-by: Lee Jones <lee@kernel.org>