ASoC: wcd9xxx: Reset MBHC registers upon plug removal

Reset MBHC Scaling mux and release detect when mechanical
plug removal is detected. This is to ensure that there is
no micbias voltage present when plug is removed immediately
after insertion.

CRs-fixed: 564412
Change-Id: Ie116017b81f1ecd41e3bc080b798d6d9a51a5e70
Signed-off-by: Phani Kumar Uppalapati <phaniu@codeaurora.org>