arm64: dts: allwinner: h6: tanix-tx6: Add SPDIF

Tanix TX6 board has SPDIF connector in form of 3.5 mm jack.

Add support for it.

Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20211115201112.452696-1-jernej.skrabec@gmail.com