ASoC: AQT1000: Add API for adjusting the micbias voltage on AQT1000

AQT1000 codec supports multiple micbias voltage settings. Add an
API to client modules to adjust the micbias voltage based on their
desire voltage requirements.

Change-Id: If89b836ab60b66e9ec1000fe6d07f4b1a8484b01
Signed-off-by: Sudheer Papothi <spapothi@codeaurora.org>