ASoC: rockchip: spdif: Add support for format S32_LE

ASoC: rockchip: spdif: Add support for format S32_LE

Treat 32 bit sample width as if it was 24 bits using only the
24 most significant bits.

[I've merged the channel-swapping fix from Zohn Ni into Sugar Zhang's
patch introducing the problem in the first place]

Co-developed-by: Zohn Ni <zohn.ni@rock-chips.com>
Signed-off-by: Zohn Ni <zohn.ni@rock-chips.com>
Signed-off-by: Sugar Zhang <sugar.zhang@rock-chips.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://patch.msgid.link/20260203-rockchip-spdif-cleanup-and-bsp-sync-v2-8-4412016cf577@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>