ASoC: wcd9xxx: Use common functionality to change micbias voltage

Currently helicon codec driver hardcodes the micbias voltage to 1.8
volts and hence does not support micbias voltage other than 1.8 volts.
Add support for the helicon codec driver to use the existing common
drivers to be able to support micbias voltages other than 1.8 volts.

CRs-fixed: 537966, 554536
Change-Id: I3475ea744b3b2518eaa2c4153551af1a4d95afc8
Signed-off-by: Bhalchandra Gajare <gajare@codeaurora.org>