asoc: codecs: Update dmic2 support on WCD938x

As DMIC2 is muxed on same channel with MBHC
on soundwire port3 of WCD938x codec, need to set
selection bit for DMIC2 during recording usecase
over it.

Change-Id: Ice9b92eb964af25e47db4b3d8d25db07a82a9bf2
Signed-off-by: Laxminath Kasam <lkasam@codeaurora.org>