ASoC: wcd9306: Fix for audio recording

If multiple mixer widgtes share the same kcontrol,ASoC framework
will create common controls. For audio capture usecase we need
each AIF cap mixer widget to have its own control.
Change creates control for each of the AIF capture mixer widgets.

Signed-off-by: Gopikrishnaiah Anandan <agopik@codeaurora.org>