ASoC: Add Freescale SGTL5000 codec support

Add Freescale SGTL5000 codec support.
Supported features:
 - line-in and mic input
 - headphone and line-out output
 - line-in bypass ADC and DAC to headphone
 - 16, 20, 24, 32 bit audio
 - 8 ~ 96k sample rates

Signed-off-by: Zeng Zhaoming <zhaoming.zeng@freescale.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>