ASoC: msm8x16-wcd: add support to change micbias voltage

Add provision to adjust the initial micbias voltage as
required for headset detection by specifying the
voltage ranging from 1.6v to 2.85v

Change-Id: Ic52655529810b0c07e5a1d335cbc51fb7f5c1e11
Signed-off-by: Yeleswarapu Nagaradhesh <nagaradh@codeaurora.org>