ASoC: wcd: update impedance detection

Recently the formulae to compute impedance has been
modified. Update the driver to use it. Add mixer
controls to be exposed to userspace for impedance
detection. Add changes to apply proper gain after
impedance detection.

Change-Id: I9517bd7dd794f308d7fe40c49b2788d36fedbfa9
Signed-off-by: Simmi Pateriya <simmip@codeaurora.org>