arm64: dts: meson: add audio playback to nexbox-a1

Add initial support limited to HDMI i2s and SPDIF (LPCM).

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/20210804140029.4445-1-christianshewitt@gmail.com