ASoC: codecs: tlv320aic26: Demote seemingly unintentional kerneldoc header

ASoC: codecs: tlv320aic26: Demote seemingly unintentional kerneldoc header

This is the only use of kerneldoc in the sourcefile and no
descriptions are provided.

Fixes the following W=1 kernel build warning(s):

sound/soc/codecs/tlv320aic26.c:138: warning: Function parameter or
member 'dai' not described in 'aic26_mute'
sound/soc/codecs/tlv320aic26.c:138: warning: Function parameter or
member 'mute' not described in 'aic26_mute'

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Link: https://lore.kernel.org/r/20200709162328.259586-10-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>