ASoC: wcd-mbhc: correct headphone detection

Characteristics of 3pole extn cable is, MIC is grounded
and HPHL and HPHR are floating. In current SW, if
there is GND_MIC SWAP with button press cable is reported
as unsupported. Hence report cable as headset if there is
GND_MIC SWAP with button press.

CRs-Fixed: 963833
Signed-off-by: Yeleswarapu Nagaradhesh <nagaradh@codeaurora.org>
Change-Id: Ie6b467292661358699fcab6263653139cda87c33