arm64: dts: amlogic: g12a-u200: add missing AVDD-supply to acodec

This fixes the following:
audio-controller@32000: 'AVDD-supply' is a required property

Tested-by: Christian Hewitt <christianshewitt@gmail.com>
Link: https://lore.kernel.org/r/20240606-topic-amlogic-upstream-bindings-fixes-dts-v1-7-62e812729541@linaro.org


Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>