Add Voice DAI to support the PCM voice interface of the twl4030 codec.

The PCM voice interface can be used with 8-kHz(voice narrowband) or
16-kHz(voice wideband) sampling rates, and 16bits, and mono RX and mono
TX or stereo TX.

The PCM voice interface has two modes
 - PCM mode1 : This uses the normal FS polarity and the rising edge of
               the clock signal.
 - PCM mode2 : This uses the FS polarity inverted and the falling edge
               of the clock signal.

If the system master clock is not 26MHz or the twl4030 codec mode is not
option2, the voice PCM interface is not available.
Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>