ASoC: rockchip: spdif: Add support for rk3568 spdif

This patch adds support for rk3568 spdif which is the same
with rk3366.

Signed-off-by: Sugar Zhang <sugar.zhang@rock-chips.com>
Link: https://lore.kernel.org/r/1629800162-12824-4-git-send-email-sugar.zhang@rock-chips.com


Signed-off-by: Mark Brown <broonie@kernel.org>