ASoC: wcd-mbhc: Fix high impedance lineout detected as headphone issue

During playback if lineout is inserted it is detected
as lineout then changed to headphone. This is because
we do not compute impedance again as pa is on. Force
jack to be detected as lineout based on initial detection
to resolve the issue.

Change-Id: I243c324dcd251596db97aeef07b8535986550650
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>