ASoC: wcd934x: Add impedance detection controls

Add impedance detection mixer controls used to get
the impedance values of headphone left and right
channels.

CRs-Fixed: 1083198
Change-Id: Ibbca465192c58deba3618d70e36089119c7f3994
Signed-off-by: Phani Kumar Uppalapati <phaniu@codeaurora.org>