mfd: twl4030_codec: Remove unused and duplicate audio_mclk fields

audio_mclk can be queried from mfd driver. Therefore, it is not
needed in twl4030_codec_audio_data or in twl4030_codec_vibra_data
anymore.

Signed-off-by: Ilkka Koskinen <ilkka.koskinen@nokia.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>