ASoC: wcd: update mbhc driver to release pm wake lock

MBHC driver moves pm wake lock state to awake before
scheduling work which detects the headset type.
But the work scheduled does not move the pm wake lock
state back to sleepable. This is causing the target
not to enter into tcxo.

CRs-Fixed: 681157
Change-Id: Ib8d94d5d50a8180365ba4fdaee7c4c587769cbe4
Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>