ARM: dts: msm: enable VA macro island mode MUX select on Kona

VA macro is currently lacking capability to dynamically select
island mode on Kona. Add a DT property for VA macro to provide this
capability in driver.

Change-Id: If411ac6dc6e7b9a8a3674bfc492153f6637d11d5
Signed-off-by: Xiaoyu Ye <benyxy@codeaurora.org>