asoc: lahaina: add support for aud_ref_clk_sel mux

External mclk to audiocc can be routed via
ext_mclk1_a or ext_mclk1_b gpio on lahaina by configuring
aud_ref_clk_sel mux. Add changes to configure aud_ref_clk_sel
mux in machine driver based on DT property.

Change-Id: I606cb148113263a53d6ad02011db0c5c8d042126