dt-bindings: ata: ahci-platform: Add power-domains property

Some SoC using power-domains property so add it here

Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220311210357.222830-5-linux@fw-web.de