ASoC: msm: Enable support to detect headsets with threshold on mic

When headset with threshold on mic is detected, we should maintain
mic bias all times even with audio playback in progress and we
should not switch to VDDIO. Otherwise, headset button press will
not be detected and sometimes we might get headset removal interrupt
after calibrating the thresholds to VDDIO.

Change-Id: I270bbad85ac7c4aaa44bfe0104df04f5203d476a
Signed-off-by: Phani Kumar Uppalapati <phaniu@codeaurora.org>