asoc: bolero: enable VA macro island mode MUX select on Kona

VA macro is currently lacking capability to dynamically select
island mode on Kona. Add support in VA macro driver to read MUX
selection register from DT to enable dynamic island mode select.

Change-Id: I5462265fffcc6d6bbb3ff6eead5f44f0b8909141
Signed-off-by: Xiaoyu Ye <benyxy@codeaurora.org>