ASoC: fsl_spdif: Silence output on stop

Clear TX registers on stop to prevent the SPDIF interface from sending
last written word over and over again.

Fixes: a2388a49 ("ASoC: fsl: Add S/PDIF CPU DAI driver")
Signed-off-by: Matus Gajdos <matuszpd@gmail.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20230719164729.19969-1-matuszpd@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/fsl/fsl_spdif.c

@@ -751,6 +751,8 @@ static int fsl_spdif_trigger(struct snd_pcm_substream *substream,
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
 		regmap_update_bits(regmap, REG_SPDIF_SCR, dmaen, 0);
 		regmap_update_bits(regmap, REG_SPDIF_SIE, intr, 0);
+		regmap_write(regmap, REG_SPDIF_STL, 0x0);
+		regmap_write(regmap, REG_SPDIF_STR, 0x0);
 		break;
 	default:
 		return -EINVAL;