ASoC: wcd9xxx: Update button release thresholds based on current micbias

During short button press, the button release threshold
registers are updated based on the determined button number
so that when mic voltage goes above the programmed value,
release interrupt will be triggered. This reduces delay in
reporting button release. However, the release thresholds
should be programmed based on the current micbias voltage
instead of programming based on 2.7V micbias. Otherwise,
it is possible that during playback where micbias is switched
to VDDIO (1.8V), the mic voltage would never go beyond the
voltage programmed in release threshold registers there by
not generating release interrupt at all.

CRs-Fixed: 641486
Change-Id: Ied9891f88b89d6f972db5e197200886c6aab3ab2
Signed-off-by: Phani Kumar Uppalapati <phaniu@codeaurora.org>