ARM: dts: msm: Add support to enable VA MCLK MUX select on Kona

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

Change-Id: Iabafc0b941927ad8a74434417226668e145937d0
Signed-off-by: Xiaoyu Ye <benyxy@codeaurora.org>