ASoC: Fix typo in kernel doc comment for snd_soc_put_volsw_sx()

Spotted by kbuild bot:
 sound/soc/soc-ops.c:415: warning: No description found for parameter 'ucontrol'
 sound/soc/soc-ops.c:415: warning: Excess function parameter 'uinfo' description in 'snd_soc_put_volsw_sx'

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@kernel.org>