ASoC: msm8960: Fix button detection voltage thresholds

Recent measurements indicate that the button threshold voltages
have changed. Adjust the button voltages accordingly

CRs-fixed: 390846
Change-Id: Ida72b0f9ab79e081901c733cdff083f0e983e6de
Signed-off-by: Bhalchandra Gajare <gajare@codeaurora.org>