ASoC: sdm660_cdc: Fix pop noise issue at DMIC

Pop noise occurs during switch from handset to speaker mode
during voice call. This is because sufficient delay
is not provided for tx to unmute. A delayed workqueue
that will do unmute at the end solves the issue.

CRs-Fixed: 2101423
Change-Id: Idc1fd8e770eb0d361bd436ce35940200173106ef
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>