ASoC: reduce verbosity of error messages for sof-dai and sof-link

Recent changes result in multiple dmesg traces such as:

[ 14.410435] Audio Port: ASoC: error at snd_soc_link_startup on Audio
Port: 1

[ 14.410446] sst-mfld-platform sst-mfld-platform: ASoC: error at
snd_soc_dai_startup on media-cpu-dai: 1

These messages are not really errors, when dai and dai-link callbacks
return the value of e.g. snd_pcm_hw_constraint_single() the result is
"Positive if the value is changed, zero if it's not changed, or a
negative error code"

Add a simple test to skip the checks for positive returned values
Suggested-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200529123613.13447-1-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-dai.c

@@ -14,10 +14,14 @@
 static inline int _soc_dai_ret(struct snd_soc_dai *dai,
 			       const char *func, int ret)
 {
+	/* Positive, Zero values are not errors */
+	if (ret >= 0)
+		return ret;
+
+	/* Negative values might be errors */
 	switch (ret) {
 	case -EPROBE_DEFER:
 	case -ENOTSUPP:
-	case 0:
 		break;
 	default:
 		dev_err(dai->dev,

sound/soc/soc-link.c

@@ -12,10 +12,14 @@
 static inline int _soc_link_ret(struct snd_soc_pcm_runtime *rtd,
 				const char *func, int ret)
 {
+	/* Positive, Zero values are not errors */
+	if (ret >= 0)
+		return ret;
+
+	/* Negative values might be errors */
 	switch (ret) {
 	case -EPROBE_DEFER:
 	case -ENOTSUPP:
-	case 0:
 		break;
 	default:
 		dev_err(rtd->dev,