ASoC: mbhc: Avoid multiple insertion/removals for aux cable

High impedance aux cable when inserted causes jack to change to
lineout. This causes removal event to be called which results
in pause during music playback because jack value is not updated.
Do not change current plug while plug is marked as lineout.

CRs-Fixed: 2151012
Change-Id: I8bdc662d7495a0def667cb1d2549a636c5467bac
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>