dt-bindings: power: Add Allwinner D1 PPU

The Allwinner D1 family of SoCs contain a PPU power domain controller
separate from the PRCM. It can power down the video engine and DSP, and
it contains special logic for hardware-assisted CPU idle. Other recent
Allwinner SoCs (e.g. TV303) have a PPU with a different set of domains.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Link: https://lore.kernel.org/r/20230126063419.15971-2-samuel@sholland.org
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>