ASoC: wcd-mbhc: add support to read new headset detection parameters

To config different headset detection parameters for different hardware, add
two new headset detection parameters in device tree and read it in mbhc driver.

Change-Id: I10457b7d5eae54eba8a4cd273885a63ebad3ccb3
Signed-off-by: Meng Wang <mwang@codeaurora.org>