ASoC: core: Return -ENOTSUPP from set_channel_map() if no operation provided

It makes it easier for common code to work with snd_soc_dai_set_channel_map()
by distinguishing between operation not being supported and an error.
This is done inline with others snd_soc_dai.* apis.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20190703123002.12427-1-srinivas.kandagatla@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-core.c

@@ -2614,7 +2614,7 @@ int snd_soc_dai_set_channel_map(struct snd_soc_dai *dai,
 		return dai->driver->ops->set_channel_map(dai, tx_num, tx_slot,
 			rx_num, rx_slot);
 	else
-		return -EINVAL;
+		return -ENOTSUPP;
 }
 EXPORT_SYMBOL_GPL(snd_soc_dai_set_channel_map);