ASoC: soc-component: Add comment for the endianness flag

Add a comment to make the purpose of the endianness flag on the
snd_soc_component structure more clear.
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20220504170905.332415-2-ckeepax@opensource.cirrus.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/sound/soc-component.h

@@ -169,6 +169,15 @@ struct snd_soc_component_driver {
 	unsigned int idle_bias_on:1;
 	unsigned int suspend_bias_off:1;
 	unsigned int use_pmdown_time:1; /* care pmdown_time at stop */
+	/*
+	 * Indicates that the component does not care about the endianness of
+	 * PCM audio data and the core will ensure that both LE and BE variants
+	 * of each used format are present. Typically this is because the
+	 * component sits behind a bus that abstracts away the endian of the
+	 * original data, ie. one for which the transmission endian is defined
+	 * (I2S/SLIMbus/SoundWire), or the concept of endian doesn't exist (PDM,
+	 * analogue).
+	 */
 	unsigned int endianness:1;
 	unsigned int non_legacy_dai_naming:1;